ROOMS-251: Theme rooms unit edit form.

@istos, this commit adds similar styling for the Unit Type Edit form as that found on the Unit Edit form.

I had to do some jiggerhoochy  to wrap some of the form elements inside additional fieldsets that allowed for this layout while maintaining the "data" wrapper element "#tree" (which is required for the auto-save array/object magic on form submit).  This could look cleaner if we could get that intermediate "data" thingy out of there, but this is an exercise I'll leave to maybe @plopesc, seems low priority.

![rooms-251](https://cloud.githubusercontent.com/assets/243532/2830450/c32b9e50-cfae-11e3-8436-e2f1f5137f7b.png)