Sarina/more ins dash

A few things I forgot in my last PR.

* Internationalization
* Completely remove unused enrollment code from the Student Admin page (template & coffeescript) - we decided to only expose enroll/unenroll feature on the Membership page, because that's where we can provide email notification 

Review: @adampalay @flowerhack 

@singingwolfboy can you very quickly verify I did the i18n here correctly?