Merge pull request #42 from phuongnq/master

hide back button when user logout
Merge pull request #43 from phuongnq/master

add myCode when registering
Refactoring upload video

Set timeLimit for recording and picking video: 2 minutes
Minor refactoring
Merge pull request #44 from phuongnq/master

add promotion info when registered
plus/minus point on comment