refactoring code.Browser.js, add code-tree toggler
fix #298
attachment: Add moveTo method.

moveTo method moves self to another container.
user: Do not allow a nonimage for avatar.

* Client: Alert if user upload nonimage for avatar.
* Server: Do not update avatar if the new one is not an image.
Merge pull request #299 from laziel/codebrowser-130701

코드브라우저 개선 작업
Merge pull request #301 from npcode/fix/upload-avatar-image

Do not accept a non-image file as user's avatar.
fixed #250
fixed #303
Changed the counter class
Added font-awesome icons
Refactoring Fork-PullRequest list view
Moved the forking project list to the fork button
Added pull-request counts to the list tab