Also improve efficiency of the mastodon:maintenance:add_static_avatars task

* Unite all mandatory rake tasks in mastodon:daily
Add mastodon:media:remove_remote task
Make mastodon:maintenance:add_static_avatars more resilient to exceptions

* Fix typo in task description

Before it cleared out user records only (e-mail, password) without
freeing up the associated username (account record). Furthermore, since
these records have no dependent records (due to no user activity)
they can be deleted quickly with delete_all instead of destroy

* Add tasks for open/close registration

* Code climate style fix

* Use true instead of string 'true'

* add task in order to delete unconfirmed user

* change 7 days to 2

* When avatar/header are GIF, generate static versions.
Account API returns "avatar"/"avatar_static", "header"/"header_static"
Static version is the same as original for other cases
Web UI de-animates avatars in toots, lists of users

Fix #441, fix #596, prerequisite for #1064

* Fix JS test

* Add rake task to generate static avatars/headers from GIF ones, add test

* Adds task to confirm user by email.

* Adds documentation for manual confirmation.

before. In the API, attachments now can be either image, video or gifv. Gifv
is to be treated like images in terms of behaviour, but are videos by file
type.

redis-backed "mentions" timeline as redundant (given notifications)

(without avatar). Also improved search position of exact matches

Only distribute statuses to followers who signed in in the last 2 weeks, add rake task for clearing feeds of inactive users

to the API

respect hub.lease_seconds (fix #46)

and atom feed generation to some extent, as well as the way mentions are
stored

local followers. Remote users' usernames SHOULD be case-sensitive