workaround UCM variable replacement

UCM can't do variable replacement in assets - like main.js, so we need to do it elsewhere.

I had hoped to be able to this in a more angular fashion, but ng-model to bind the variable to the scope didn't work.  I think the bind occurred too late in the process, and the template config was already done.  So, I'm using a global variable instead.  For now, at least.  

I'm open for suggestions to avoid a global variable.