Clean up build email fixes. 

Send the notifications from the web celeries for now.
Clean up tasks.py a bit
Add start of base email template, add general multipart mailer

Adds multipart mailer and a semi-mocked up email example.
Fix up lingering email issues, some content changes
Slight change on build failure email
Add Syncer backend
Generate latest version on project save
Whitespace cleanup
Properly save model
Create build objects on the server not the client.
Add proper settings for syncers
Refactor tasks for double remote usage
Merge remote-tracking branch 'origin/fix-build-emails' into syncer-backend

Conflicts:
	readthedocs/core/utils.py
	readthedocs/projects/tasks.py
Allow web tasks to work without API
Rejigger tasks
Finish cleaning up web tasks
Clean up move_files and make sure it happens when it should.
Clean up web tasks and add commit to imported file
Clean up state handling in setup_vcs
Fix imported file deletion, and make move_files a task