EmberSync.Queue should run when a job is enqueued, rather than on an poll-interval

[tute]

Calling processNextJob when there's no jobs pending seems to make little sense. Queue could run on each enqueue, and start the retry intervals only on job error. If app goes offline for hours though, it may make sense to offer an API to retry it manually, or on a window.addEventListener('online', callback) event.

[kurko]

Makes total sense. If no one does it, I'll do it myself likely in a month from now.