added detail view for each resource + mathjax working again

Improvements:
- added piwik goal tracking for analysis of semi-public testphase
- revised footer now includes link to feedback form
- enable editing and deletion of single resources works
- fixed mathjax-rendering in resultsetview and ck-mathjax dialog

Pending:
- allow users to manipulate the tag-filter per item
- enable pasting of HTML sources into resource a field
- enable users to edit and delete tags in single-resource/detail view

To be tested.