initial favorites implementation
immediate
changes for student and challenges pages
only show favorite badge when logged in.
use red for active
some ui tweaks
ajaxify
Merge branch 'master' of github.com:camilaachutti/curiosityMachine

Conflicts:
	challenges/models.py
	challenges/templates/challenges.html
	challenges/views.py
	curiositymachine/templates/base.html
Merge branch 'feature/favorites'

Conflicts:
	challenges/templates/_challenge_item.html
	challenges/templates/challenges.html
	challenges/views.py
	profiles/templates/student_home.html
merged migration changes