Angular Prototype for Repository Editor

- Added a controller specific to the repository editor form
- Added a directive specific to the repository editor form
- Added a couple generic directives that would have an application-wide usage
- Changes made to RepositoryController (@edit related changes)
- Added a JS function to display flash messages triggered through Angular events
- Added Jasmine tests

#1064
Merge pull request #1219 from AparnaKarve/angular_repo_editor

Angular version of Repository editor