introduced header-toolbar + sorting and filtering of resultsets.

Improvements:
- up/downvoting of resources works fine (and in AJAX-style)
- client-side model set/getTagFilter is in use
- reorganized the various parts of the code in trt.js

Administrative:
- added repo:Prinzhorn/skrollr to this repo

Pending: mathjax-rendering to be fixed, styling and a DELETE-command.