Added feature test for term filtering

Renamed feature test for filter to filter_panel

wip search term filtering

done
Added feature test for filtering by "Datei"
Added feature test filter by permissions
Added feature tests, each mainlevel has at least one test
Added feature tests for applying multiple filters within a group
Added feature test for combining filters from different filter groups
Added feature test for resetting all filters
Added a feature test for reseting single filters
Removed olde filter_panel feature file
HOTFIX: only user/owner can destroy media_resource via media_resources#destroy
Added spec for deleting a resource via controller
Appropriate response on DELETE MR, improving quick hack from last night

  DELETE on media_resource responds only to json and with correct
  HTTP status.
[WIP] tests for access delete actions
[FINISH] test access delete on interface
Removed meaningless test from filter_panel and marked one pending
Merging fix and test for deleting a media resource

Merge branch 'next'