Minor renaming of test
WIP: adapt tests to the migration from Resque to Sidekiq
WIP: migration from Resque to Sidekiq.

Several minor changes:

- fix bug when unscheduling updates for a feed. The argument passed is a feed id, not a feed object.
- when scheduling the first update for a feed just after creating it, do not look for other updates of the feed to unschedule them. We're sure that there are no updates scheduled for a just created feed, it makes no sense to waste time looking for them.
- some test changes to adapt to Sidekiq
WIP: adapt tests to the migration from Resque to Sidekiq
WIP: migration from Resque to Sidekiq

Fixed bug: no feed id was passed when scheduling missing feed updates.
WIP: adap tests to the migration from Resque to Sidekiq