feat(click): Improve click interaction in cockpit

- Improve click interaction handling
- add 'ctrl'-key support to be able to select more than one element in
  diagram or one node in tree
- refactoring of cockpits' layout (deletes some directives, which were
  responsible to resize div elements on window resize, now it is full with
  css)

related to CAM-719
Merge branch 'master' of github.com:camunda/camunda-bpm-platform