Move copy, cut, paste, undo, redo into their own actions

* This removes the need to check the ApplicationModels action type
* Implemento redo/undo
* Add tests for redo/undo
* Leave cut copy paste empty for now
Give each PIPE action it's own class e.g. AddTokenAction

* InhibitorArcs can now be added
* Removes the swith statements from mouse handler and replaces with a call to doAction(..)
* Still to do select/drag
Merge pull request #17 from sarahtattersall/inhibitor_arc

Inhibitor arc