Merge pull request #9 from jwiemers/redesign

frontend apdex overview
better support for frontend apex on minutes and totals
fixed apex overview for good
removed frontend_overview controller action
assorted bug fixes
support plotting ajax_time
fixes Issue #10 and #11 resolves merge conflicts
allow errors header to break
some polish and removed the link to the global dashboard
Merge branch 'redesign' of github.com:skaes/logjam_core into redesign
fixed #11 grouping bar color while sorted by apdex
#15 resolve the navigation issue (frontend timings)
#14 fixed some navigation issues and added a new mediaquery for extreeeeem big screens, currently working just for backend resources
fixed a small issue with on the frontend view
#16 fix the offcanvas navigation and the xxl view