* Add overview of active sessions

* Better display of browser/platform name

* Improve how browser information is stored and displayed for sessions overview

* Fix test

* Fix #2347 - Bind web UI access token to session

When you logout, session also destroys the access token, so it's no longer
valid. If access token is destroyed some other way, the session is also
destroyed, requiring a re-login.

Fix #1681 - Add scheduler to remove revoked access tokens and grants

* Fix test

* Add spec files for feed and media cleanup workers

* Add coverage for feed and media cleanup schedulers

* Clean up feed and media cleanup workers

sidekiq-scheduler jobs

Resolves #2495

* Fix Scheduler::SubscriptionsScheduler, add worker test for it

* Change production log level of Sidekiq to "warn" instead of "info"

* Fix #2473 - Use sidekiq scheduler to refresh PuSH subscriptions instead of cron

Fix an issue where / in domain would raise exception in TagManager#normalize_domain

PuSH subscriptions refresh done in a round-robin way to avoid hammering a single
server's hub in sequence. Correct handling of failures/retries through Sidekiq (see
also #2613). Optimize Account#with_followers scope. Also, since subscriptions
are now delegated to Sidekiq jobs, an uncaught exception will not stop the entire
refreshing operation halfway through

Fix #2702 - Correct user agent header on outgoing http requests

* Add test for SubscribeService

* Extract #expiring_accounts into method

* Make mastodon:push:refresh no-op

* Queues are now defined in sidekiq.yml

* Queues are now in sidekiq.yml