Prototype queue processing for actions.
add rq to requirements
rq test fixture
unit tests for local client actions
Reset the action queue after every test
implement and test local thread copy
Better docstrings for FolderItem/ImapUid
[SCHEMA] add inbox folder name cols to imapaccount
IMAP sync backends now save folder names when sync starts.
Less ambiguous name for test_events.py
Remove duplicate lower() call.

We already make sure all members of existing_labels and new_labels are
lowercase.
Canonicalize All Mail to be 'archive' in our datastore
Update test dump for new ImapAccount columns
Canonicalize folder_names keys as lowercase

As a part of this, I'm also simplifying the logic in Gmail's
folder_names() detection to get rid of the janky usage of
boolean flags.
Update local actions to take advantage of new datastore folder abstraction
Ow, that's a bug
Add redis-server to VM deps
Add a backref to message to access associated imapuid
implement gmail syncback actions
stub out syncback tests