[WIP] 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 (WIP - need to add a few more)

#1064
@eclarizio Currently the directives track the validity of the input element only via the actual user input, as in keystrokes. Therefore when the original valid values are copied over, since there is no user input as such, the functions in the directives that would have set the form to its valid state do not get triggered, hence the need to set the form to valid explicitly.
But you are correct, this should have been taken care for us automatically.
Let me look into it.