Workflows: AMD compatible and flightJS

* Complete rewrite of Holding Pen front-end JavaScript using FlightJS. Is cool.[*]
* Removes old workflows admin interface and superseded JS files.
* Adds missing prefix for Holding Pen cache keys.

[\*]  *Given the huge amount of changes, some functionality is still not 100% and even some debug code might linger. This will be improved upon in near future, but the gist of the functionality is there.*