Change skill level names to more readable form by users. (BEG --> Beginner, etc.)
Implement Course Listings Page
Use cdn (content distribution network) for javascript libraries
Link course button in navbar to course listings page. Update url referencing for other buttons.
Update datetime display to more readable form.
fix merge conflicts.
fix atsu's goof-up
Fix tab on course listings. Fix filtering for upcoming and all courses.
Merge pull request #53 from calblueprint/byron/course_listing

Byron/course listing