limit how many students user invite to course
removed redundant variable assignment
enabled create course form, added upsell messaging
upsell message on the invite students form
course limit check in the form, just in case
Merge branch 'refs/heads/appsembler_develop' into feature/147-limit-student-invites
switched call to action messages between two templates
added tests for invite students limit call to action
added tests for the upgrade plan call to action on course create page
fix to avoid changing mediathread fixtures
removed unused imports
pep8 whitespace fix
forgot to add a test_ prefix to a unit test
Merge branch 'refs/heads/appsembler_develop' into feature/147-limit-student-invites

Conflicts:
	media/css/mediathread.css
	mediathread/course/tests/test_views.py
	mediathread/settings_shared.py
	mediathread/templates/base.html
hide invite students form and call to action bar when there are no invites remaining
made the remaining invites count more prominent
Merge pull request #31 from appsembler/feature/147-limit-student-invites

#147 - Limit number of courses and invites