Summary:
Message list can be narrower
Account sidebar is narrower
Never open new windows on single click
Blue send button
Clean up cruft from draft deletion
Render composer empty, setProps when draft populated
Use new `pristine` attribute to discard un-changed new drafts
_addToProxy needs deep equals to prevent "save to = [], cc = []"
Mark as read on click, not afterwards
Allow toolbar / sheet items to style based on the workspace mode
specs covering draft unloading / behavior of cleanup
Always, always reset mode to spec after each test
New tests for destroy draft functionality
Test Plan: Run a handful of new tests
Reviewers: evan
Reviewed By: evan
Differential Revision: https://review.inboxapp.com/D1335
