Summary:
This is a critical patch that fixes two problems with the task queue:
1. Tasks in Status: Retry are retried the next time processQueue is run,
which could be pretty much immediately. Certain scenarios lead to tasks
running in a hard loop forever.
2. Returning Task.Status.Retry set the retry flags on the task but did not
schedule the queue to be processed again. So if only a single item in the
queue was present, it might never be retried again until the user performed
another action.
Test Plan: Where did the specs for TaskQueue go? There aren't many... need to write more.
Reviewers: evan
Reviewed By: evan
Differential Revision: https://phab.nylas.com/D2762
