First attempt at #1471:  Allow becoming fan of a project
Merge branch 'develop' of github.com:ImaginationForPeople/imaginationforpeople into feature/project_fan

Conflicts:
	apps/project_sheet/views.py
Deal with review comments, which turned out to imply significant HVAD related changes.
Merge branch 'feature/project_fan' into develop

Conflicts:
	apps/project_sheet/views.py
added haystack setting in site_settings with switch between Whoosh and SolR