add dashboards

  - create dashboards & dashboards_graphs tables
  - unify graphs/dashboards display, using dedicated controllers
  - put sidebar in partial to display it from any controller
add system dashboard
add more dashboards
fix dashboard load & remove cleanup task
Merge pull request #32 from josqu4red/dashboards

Dashboards
Merge remote-tracking branch 'upstream/master' into better_graphs

Conflicts:
	app/assets/javascripts/app.js.coffee