professor messaging infra structure
adding course to ProfessorMessage
viewsets for professor message
missing send_mail import
Merge branch 'master' into professormessages
adding validation to professor message serializers
Merge branch 'master' into professormessages
Merge branch 'master' into professormessages
email templates no banco
Merge branch 'master' into professormessages
php activities rules
added SITE_* settings
use SITE_HOME to set the home page
added context processor to make site settings available in templates
Merge branch 'master' into professormessages

Conflicts:
	timtec/urls.py
initial files for messages angular module
fixing #327, adicionando checagem de existencia de video antes do play. Resolve pra qualquer caso.
Merge pull request #328 from mupi/timtec/issue327

add check for existing video before playing, fixes #327
Merge pull request #319 from barraponto/site_abstract

abstracting TIMTec details
partial implementation off professor messages