fix(serviceTask/prop): Add disable button.

- "choose class" button is disabled when the associated radio button is not
  selected

related to #CAM-212
fix(focus): Delete focus on radio button text field.

- focus should not be set on radio button text field when a value exists
  because it is not possible to delete the bpmn element

related to #CAM-1361
feat(throwingSignalEvents/prop): Add async flag for throwing signal
events.

- delete async flag for throwing signal events from general tab on
  properties panel and add it to the event tab
- only the async flag is supported by the camunda bpm engine for these
  elements, not the retry cycle strategy

related to #CAM-1378
fix(add-lane): fix flow-node-refs not properly being updated

This fixes the bug that flow node refs are not properly updated
when a lane is added to a pool.

For some strange reason, the bug does only popup on Eclipse Kepler.

Closes CAM-1382
Merge branch 'master' of github.com:camunda/camunda-modeler
feat(targetNamespace): Add field to edit target namespace.

- add new tab "document" on properties panel, because target namespace is
  part of definitions and definitions tab is not the best position
- it is possible to edit "target namespace" of the diagram on the
  definitions tab

related to #CAM-1235
Merge branch 'master' of github.com:camunda/camunda-modeler
feat(morph/activities/gtw): Morph bpmn elements

- it is possible to morph a created bpmn element into another bpmn element
- for example it is possible to morph a service task into a user task etc.

related to CAM-303
Merge branch 'master' of github.com:camunda/camunda-modeler
Merge pull request #3 from camunda/master

Merge camunda master