Add video search by title
Add function recent_videos to Catogery to show at most 6 recent videos
Show recent 6 videos for each category in home
Add search UI and view
Add a test case to Video search_by_title : when title is empty
improve video spec and return empty array if search_term is blank
Reimplement Category.recent_videos
revise category spec
Create User and test
Change User field, use password_digest instead
Add bcrypt to use has_secure_password in User
Add register and sign_in page
Implement User create
Update has_many condition for rails 4
Add authentication
Config header to show user's name after login
Move require_log_in from application_controller to necessary controller
Merge pull request #2 from jychen7/week1b

Week1b