Dglance restapi

Ok - there is quite a lot here:

Support for multi-site - this uses a context_processor for some SITE settings - that drives the site titles, use of CSS files etc. 

Support for extra db driven course information - used in overview pages and in preview mode.

Support for logon from landing page - institution courses only show up if logged in as a institution person. 

May need some code checks and tidy ups - definitely needs testing