branch +edit doesn't load picker JS for pretty UI elements

We did some talking around this and we've had to add a bunch of custom templates for blueprints, branches, etc that's only purpose is to extend generic-edit.pt to load a javascript module that runs on the page.

The best way to get at this would be to create a new generic-edit-withjs.pt which adds two attributes to the python View.

1. JS Module name
2. JS View class name

Then this .pt could be hard wired to create a YUI block that includes the proper JS module from the python View property and runs the simple two line bootstrap:

    var view = new $classname()
    view.render();

Since we've got YUI 3.5 and we've started to use YUI View objects the API would be consistant and it would also help enforce that all JS goes into a JS file that can be tested vs the .pt file which isn't.

Or as abently brought up to add these attributes to the current default generic view and update the generic-edit.pt to add the YUI block if the attributes are defined.

Actually, I meant that we could update the base template to add the YUI block if the attributes are defined, so that we can use the same mechanism to load JS whether or not we're using generic-edit.