* Remove Salmon and PubSubHubbub endpoints

* Add error when trying to follow OStatus accounts

* Fix new accounts not being created in ResolveAccountService

* Fix URI not being sufficiently validated with prefetched JSON

* Add additional id validation to OStatus documents, when possible

Additionally, ActivityPub::FetchRemoteStatusService no longer parses
activities.
OStatus::Activity::Creation no longer delegates to ActivityPub because
the provided ActivityPub representations are not signed while OStatus
representations are.

* Add support for searching AP users

* use JsonLdHelper

* Do not raise unretryable exceptions in ResolveRemoteAccountService

* Removed fatal exceptions from ResolveRemoteAccountService

Exceptions that cannot be retried should not be raised. New exception
class for those that can be retried (Mastodon::UnexpectedResponseError)

* Rescue exceptions related to Goldfinger

* Exclude Goldfinger::SSLError

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)

* 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

The goal of this change is to enhance Mastodon's handling of remote domains
for which the APIs reside on a different host (see issue #1032).

Indeed, when a remote user unknown to Mastodon is mentionned, only its profile
URL (e.g. https://social.example.org/users/User) is known, and Mastodon has to
build a @username@domain handle for it. To do so, Mastodon fetches the user's
atom feed (e.g., https://social.example.org/users/User.atom) and uses its
content to get the username part of the handle, and the URL's host part to
build the domain (e.g., @User@social.example.org). This handle is then used
for a Webfinger request.

In the case where example.org serves the Webfinger info for @User@example.org
and all feeds and APIs are hosted at social.example.org, Mastodon will still
build @User@social.example.org and fail at resolving the account's details
through Webfinger.

This patch changes this behaviour by using the author's email address from
the atom feed to build the handle. In Mastodon-generated atom feeds, the
email address is always the handle it expects for federation.

add ability to open status by URL from search (fix #53)

if account lock info was up to date, otherwise re-do the FollowService
with now updated information

production as it's very verbose and not very useful

Fetching atom extracted from FetchRemoteAccountService and FetchRemoteStatusService
into FetchAtomService. Mentions of the constant "http://activityschema.org/collection/public"
skipped as it's not a real URL/user.