feature preview framework
Merge branches 'settings-redo' and 'feature-preview' into scratch

Conflicts:
	corehq/apps/domain/urls.py
	submodules/toggle
Merge remote-tracking branch 'origin/master' into feature-preview
change button color to blue
Merge branch 'master' of github.com:dimagi/commcare-hq into feature-preview

Conflicts:
	corehq/apps/domain/urls.py
Merge pull request #2990 from dimagi/feature-preview

feature preview framework