Implement filter for sport sessions
Merge with dev after fix in runnings_controller
Filter for sport sessions, resolves issue #69
Remove duplicates from locations in the filter options; add date range; remove sports filter
Change filter for location to text field

Remove unnecessary stuff (related to locations filter) from controller and user model
Adapt the older filter to the updated  index view for sport sessions
Merge branch 'dev' of https://github.com/Bergrebell/CyberCoach into dev