* Add check for missing tag param in streaming API

Fixes error:

```
TypeError: Cannot read property 'toLowerCase' of undefined
at app.get (.../streaming/index.js:493:50)
```

* Fix code style issues

* Add conversations API

* Add web UI for conversations

* Add test for conversations API

* Add tests for ConversationAccount

* Improve web UI

* Rename ConversationAccount to AccountConversation

* Remove conversations on block and mute

* Change last_status_id to be a denormalization of status_ids

* Add optimistic locking

GET /api/v1/streaming/health

Answers with OK. Fix #8337

* Support UNIX domain socket for streaming service without using PORT

The use of UNIX domain socket for streaming service was not officially supported,
but it was made unofficial to use by setting a path to PORT.
From now on, SOCKET will be used just like setting for puma.

* Hundle relative path

* Added a timeline for Direct statuses
* Lists all Direct statuses you've sent and received
* Displayed in Getting Started
* Streaming server support for direct TL

* Changes to match other timelines in 2.0

On an unhandled worker exception, we should log the exception
and exit with nonzero status, instead of letting workers
silently fail and restarting them in an endless loop.

Note: we previously tried to handle the `'error'` signal.
That's not a signal Node fires; my patch traps `'uncaughtException'`,
which is what the code was _trying_ to do.

* make it possible to stream public timelines without authorization

* Fix

* Make eslint allow `value == null`

* Remove redundant line

* Improve style and revert .eslintrc.yml

* Fix streamWsEnd

* Show IP address instead of (anonymous user)

* Add missing semicolon

* Add structure for lists

* Add list timeline streaming API

* Add list APIs, bind list-account relation to follow relation

* Add API for adding/removing accounts from lists

* Add pagination to lists API

* Add pagination to list accounts API

* Adjust scopes for new APIs

- Creating and modifying lists merely requires "write" scope
- Fetching information about lists merely requires "read" scope

* Add test for wrong user context on list timeline

* Clean up tests

* Restore streaming API output format

Regression from #4090

* Remove whitespace

* more free pgconfig for streaming by .env

* fix wrong default values

* database.yml read ENV as same as streaming server

* Fix errorMiddleware

* Add "eslint-disable-line no-unused-vars"

by using Array.prototype.indexOf instead

* Add redis key "subscribed:timeline:#{account.id}" to indicate active streaming API listeners exists.

* Add endpoint for notification only stream.

* Run PushUpdateWorker only for users uses Streaming API now.

* Move close hander streamTo(Http/Ws) -> stream(Http/Ws)End (Deal with #3370)

* Add stream type for stream start log message.

* Return 401 for an authentication error on WebSocket

* Use upgradeReq instead of a custom object

* Don't stream toots from users who have blocked the recipient user

This filter was already applied on the `/api/v1/timelines/public` API, but
not yet for the Streaming API.

* Boosted status' account_id doesn't need for filtering in streaming/index.js

This filtering is only for public/hashtag timelines, but boosts already filtered on FanOutOnWriteService because those timelines don't show boosts.

* Improve streaming API cluster logging

* Less verbose error middleware logging (stack trace useless there)

* Fix error logging

* Prevent potential issue

* Add missing "done()" in catch of Promise.all, websocket heartbeat re-implemented like in example

* I actually forgot a done(), the absolute madman

This location varies across postgres installations, and it seems like the pg
package knows how to guess correctly on each system.

Resolves #2780

* Add semi to ESLint rules

* Add padded-blocks to ESLint rules

* Add comma-dangle to ESLint rules

* add config/webpack and storyboard

* add streaming/

* yarn test:lint -- --fix

* Add <ostatus:conversation /> tag to Atom input/output

Only uses ref attribute (not href) because href would be
the alternate link that's always included also.

Creates new conversation for every non-reply status. Carries
over conversation for every reply. Keeps remote URIs verbatim,
generates local URIs on the fly like the rest of them.

* Conversation muting - prevents notifications that reference a conversation
(including replies, favourites, reblogs) from being created. API endpoints
/api/v1/statuses/:id/mute and /api/v1/statuses/:id/unmute

Currently no way to tell when a status/conversation is muted, so the web UI
only has a "disable notifications" button, doesn't work as a toggle

* Display "Dismiss notifications" on all statuses in notifications column, not just own

* Add "muted" as a boolean attribute on statuses JSON

For now always false on contained reblogs, since it's only relevant for
statuses returned from the notifications endpoint, which are not nested

Remove "Disable notifications" from detailed status view, since it's
only relevant in the notifications column

* Up max class length

* Remove pending test for conversation mute

* Add tests, clean up

* Rename to "mute conversation" and "unmute conversation"

* Raise validation error when trying to mute/unmute status without conversation

* Adding account domain blocks that filter notifications and public timelines

* Add tests for domain blocks in notifications, public timelines
Filter reblogs of blocked domains from home

* Add API for listing and creating account domain blocks

* API for creating/deleting domain blocks, tests for Status#ancestors
and Status#descendants, filter domain blocks from them

* Filter domains in streaming API

* Update account_domain_block_spec.rb

* Use babel-preset-env on Streaming Server

Change the streaming server to use babel-preset-env as well as asset compilation.
This shortens the load time at first boot.

* remove babel-plugin-lodash

* add redis-namespace gem

* namespace redis usage

* refactor redis namespace code to be less intrusive

previously : would be prepended to keys when the
REDIS_NAMESPACE env var was not set

now if it is not set the namespacing functions are
not used at all, which should prevent disruptions
when instances update.

* fix redis namespace variable style in streaming js

* remove trailing space

* final redis namespace style fix

* Replace ws with uws

* fix indent

* Adjust indentation

* remove trailing space

connection options instead of setting REDIS_HOST etc individually

Close #1986

This reverts commit 5135d609b7.