WIP on getting rid of pi-navigable-sections
fixed alignment of message count and time labels
starting huge refactor

Sheesh, what have we got here...

- split up + refactored JS controllers
- introduced services for messages + profile
- made guest view completely Angular-free
- implemented ng-view and HTML5 links
- and much, much more! (not really)
moved CSS for nav menu into its own file
fixed layout of profile view
split some functionality out of MailboxController
added source_id to Message model
added source_token for associating messages
added source_token when replying to messages
updated messages service to work better as shared data
interact directly w/ draft service from mailto directive
updated mailbox layout + added select/deselect buttons
fixed batch read/delete to use arrays, not sequences
fixed styling of open threads
updated batches controller to be thread-based
updated buttons in mailbox view
removed batch delete functionality
conditionally show/hide batch select buttons as appropriate
added Thread JS model
deleting messages is sort of working