Note: Starred is conspicuously missing. That label is being removed from the backend and exposed as "starred" which will unfortunately behave differently.
Summary:
There are now two objects, Folders & Labels. These inherit from `Category`
(that's what Eben said they were using on the backend).
There are two separate tasks.
1. MoveToFolderTask
2. ApplyLabelsTask
It turns out that the semantics between the two are quite different.
The reverse operation for moving to a folder is a bit tricky.
As of 7-8-15, the Tasks are pretty much complete. I need to write tests
for them still and do some manual testing in the client.
Test Plan: Writing specs
Reviewers: bengotow
Reviewed By: bengotow
Differential Revision: https://phab.nylas.com/D1724
