Created SiteDomainFilterBackend and closed #25
Included 2 important settings and changed requirements files way
Included sslify in prod requirements. Now need to set a prod settings with its MiddleWare
Setting a default value for file field to not leave it blank. Still need to solve this in order not to have a default value #27
Fefactored filter restriction queryset to check account from accountuser or accountgroup
Merge branch 'development' into newsletter
Refactored resource sites field test routine
Refactored submissions