* Wrap methods of ProcessFeedService::ProcessEntry in classes

This is a change same with 425acecfdb15093a265b191120fb2d4e4c4135c4, except
that it has the following changes:

* Revert irrelevant change in find_or_create_conversation
* Fix error handling for RemoteActivity

* Introduce Ostatus name space

This reverts commit 425acecfdb.

ProcessFeedService::ProcessEntry had many methods, so wrap them in classes
representing activities.

Ensure the only allowed author of top-level entries in feed is the person
the feed belongs to (a verified user). Ensure delete events only apply
if the deleted item belonged to that user.

* Actually create conversations given explicit URIs

* Try to get the parent toot in before validation, to avoid creating a new conversation

Steps to reproduce the original issue:
1. Have two remote accounts, A that you don't follow, and B that you follow.
2. Have A post a toot and reply to it.
3. Boost A's reply from remote account B.

This used to cause the local instance to get A's reply but fail to link it to
the original post.

* Try fixing ThreadResolveWorker calls

From my understanding of ActiveRecord, a transaction is commited as soon as
the exit of the outmost ActiveRecord.transaction block. However, inner
transaction blocks will exit without the transaction being commited.

In this case, ThreadResolveWorker were fired *within* a transaction block,
so moving the call out of it should do the trick. However, this is somewhat
fragile, as this whole codepath could be called within yet another transaction.

* Set status thread within the transaction block if it is immediately available from database

* Remove trailing whitespace in i18n mailers

* Use query methods instead of #present? on AR attributes

* Delegate Status#account_domain method

* Delegate Mention #account_username and #account_acct methods

* Fix nil input not handled well in AuthorExtractor concern

* Fix hard error in ProcessFeedService when replied-to status has been deleted

* Fix nil errors in ProcessInteractionService when favourited status
cannot be found

so that public timeline/caching would not encounter incomplete data

* Add index accounts on uri.

* Remove a blank line.

* 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.

* Fix conversation migration

* More spec coverage for status before_create

* Prevent n+1 query when generating Atom with the new conversations

* Improve code style

* Remove redundant local variable

Fix #2221 - Catch OpenSSL exceptions when loading remote avatars/headers/attachments
Don't strip "rel" attribute from <a> tags when sanitizing (microformats)

* Likely fix #2458, fix #2031 - handle out-of-order deletes for statuses

If a delete arrives before the original status, cache that information
for 6h, and if the original status arrives in that window, ignore it

* Add test case

Fix #2196 - Respond with 201 when Salmon accepted, 400 when unverified
Fix #2629 - Correctly handle confirm_domain? for local accounts
Unify rules for extracting author acct from XML, prefer <email>, fall back
to <name> + <uri> (see also #2017, #2172)

* downgrade rubocop 0.48.1 => 0.46.0

* exclude vendor/**/* from rubocop target files

* add frozen_string_literal comment line

* fix percent literal delimited by ( and )

* fix alignment

* remove comment disabling unknown cop

* Instead of parsing shared status contents verbatim, make roundtrip
to purported original URL. Confirm that the "original" URL is from the
same domain as the author it claims to be from.

* Fix obvious typo, add comment

* Use URI look-up first

* Add test, update Goldfinger dependency to make less useless HTTP requests per Webfinger lookup

* Fix #2119 - Whenever about to send a HTTP request, normalize the URI

* Add test for IDN request in FetchLinkCardService

* Perform IDN normalization on domains before they are stored in the DB

* Add language detection via WhatLanguage and (de)serialization of it through Atom

* Fix default language in ProcessFeedService

* Re-add newline before 'react-rails' Gem to fix groupings

Fixes Code Climate issue

The <link rel="mentioned" /> tag refers to accounts by href. So we were
matching the DB by the url attribute, and falling back to HTTP look-up.
However, GS and Mastodon use profile URLs as URIs, too, and the match
for that was missing. This could potentially alleviate some extra network
requests

Create MediaAttachment but without actual file download when domain is blocked with reject_media set to true
Clean up old media files when creating a new domain block with reject_media set to true
Return remote_url in media attachments API if local file is not present
Undo domain block action in admin UI
Ability to enable reject_media from admin UI

* Allow running mastodon on a different domain as the one used for identifying users

* Alter documentation of WEB_DOMAIN to make clear it shouldn't be used unless the admin knows what they are doing

* Compare to web_domain instead of local_domain when dealing with feeds/API

* Correctly identify mentions to local accounts

Mentions URLs point to the person's web profile, i.e., the user page served on WEB_DOMAIN.

* Fix #1141, fix #1126 - Work through UpdateRemoteProfileService for both <feed> and <entry> top-level tags

* Improve code quality, remove line unrelated to fix

about them would be processed only after the entire status is processed

status is not in the system at time of distribution; fix #607 - reset privacy
settings to defaults when cancelling replies

fix ProcessFeedService pushing status into distribution if called a second time
while the first is still running (i.e. when a PuSH comes after a Salmon slap),
fix not running escape on spoiler text before emojify

Federate spoiler_text using warning attribute on <content /> instead of a <category term="spoiler" />
Clean up schema file from accidental development migrations

fix bug in process feed service

since that is only ever called in the background

Fix #233, fix #268