ziafazal/WL-328: Multi-Site Comprehensive Theming

ziafazal: improvements need for multi-tenancy
ziafazal: fixed broken tests
ziafazal: no need to add setting in test.py
ziafazal: added hostname validation
ziafazal: changes after feedback from mattdrayer
ziafazal: fixed branding and microsite broken tests
ziafazal: make STATICFILES_DIRS to list
ziafazal: added theme directory to mako lookup for tests
ziafazal: added more protection in test_util
saleem-latif: Enable SCSS Overrides for Comprehensive Theming
saleem-latif: Incoporate feedback changes, Correct test failures, add tests and enable theming for django templates
saleem-latif: Correct errors in python tests
mattdrayer: Fix invalid release reference
mattdrayer: Update django-wiki reference to latest release