Mark failed and applied updates as pending during rollback. Fix pending_from method - in case there is no pending updates available.
Merge pull request #180 from bitzesty/rollback_fixes

Mark failed and applied updates as pending during rollback.
Change the sidekiq retry job to match the sync schedule.

The sync is run each hour, so we should retry on the same schedule.
If it fails for a day then we should stop trying.
Drop redis lock expire time

The lock is expired when something goes wrong.

Having a long lock, prevents us from doing a rollback as that requires
to obtain the lock and rollbacks are used to fix issues.