Refactoring the settings module
Merge pull request #38 from jespino/refactor-settings-module

Refactoring the settings module
Fix YT video removal in assets nuggets
Updated admin-sortables version to 1.4.9 and added zipimportx to dependencies
Merge branch 'master' of git://github.com/OpenMOOC/moocng
Added a more generic YouTube regexp to catch all the possible use cases (from list, from share list, etc.)
Replaced double quotes for single quotes to prevent string matching errors on translation.
Hardcoded input fields to obtain the date and show it to the user.

Please be aware of this instructions: http://updates.html5rocks.com/2012/08/Quick-FAQs-on-input-type-date-in-Google-Chrome the HTML5 datepicker works strictly on this format: YYYY-MM-DD and won't accept any other.
Fix typo
Added unique flag for slug fields in announcements and courses
Added missing migration file for courses model and removed debug line from youtube handler
Added badge selection to teacher admin panel
Added cleanframes management command. This command removes unused question images.
Added course field to contact form, added course to message body
Fixed missing tag in teacheradmin
Added "hidden" mode to courses. This will keep the course active but won't list it on the platform
Added hidden to allowed public modes
Added redirect of orphaned course url to courses list