* 'd' in message view opens drafts.
This also adds hotkeys within the drafts UI:
* Up/down arrow keys navigate the drafts.
* Pressing enter edits the selected draft.
* Pressing backspace deletes the selected draft.
Some variable names tweaked by tabbott.
* Created a drafts modal to display/restore/delete drafts
* Created a Draft model to support storing draft data in localstorage
* Removed existing restore-draft functionality
* Added casper and node tests for drafts functionality
Fixes#1717.