Testing closing of several dialogs

Testing opening and closing of:
- git-clone action
- help-about action
- new-project action

Also:
- setup transition-complete event on spark-overlay and listen for it in tests
- refactor access classes into separate file.
- fix several nit issues (copyright and library names)
- checking visibility with `elementFromPoint` instead of `display` / `visiblility`

@devoncarew @ussuri 
Nameless boolean `detail` is fine when it the event itself indicates some boolean state that can be on and off. Here, it looks on the calling side like the `detail` tells whether the transition has or hasn't been complete. I'd change this to:
```
asyncFire('transition-complete', detail: {"opened": opened});