Don't trigger DocumentManager.pathDeleted on document objects too soon

This effectively fixes issue #9400 byNot triggering the `DocumentManager.pathDeleted` event on document objects when `ProjectManager` calls `DocumentManager.notifyPathDeleted()` and the path has a `Document` object.

For `Document` objects , `FileSyncManager.syncOpenDocuements()` will call  `DocumentManager.notifyFileDeleted` for each `Document` object whose view needs to be destroyed and its file removed from the working set.

Prior versions of `DocumentManager.notifyFileDeleted` called `DocumentManager.closeFullEditor()` which called `removeFromWorkingSet()`; 

Now this is done in `Pane.handleFileDeleted` when the `DocumentManager.pathDeleted` event is handled.   The `DocumentManager.notifyPathDeleted` case which triggered `DocumentManager.pathDeleted` was handled by the Editor to close down Image Views.

This is safe as no other code uses this event. There are a few extensions using this event but the impact should be positive since we don't want to trigger the event until `FileSyncManager` notifies `DocumentManager` on actual deletions. For non-document objects (images) it should be OK to dispatch the event when we get it. This will be the only time we get a notification for non-document objects anyway so we *have* to do dispatch the event during `DocumentObject.notifyPathDeleted` or it won't be removed from the working set and its view closed.

Recommended Test Scenarios:

- [ ] Open a file to the working set don't change it and delete it from the file tree
- [ ] Open a file to the working set, change it and delete it from the file tree
- [ ] Open a file to the working set, don't change it and delete it from Finder/Explorer
- [ ] Open a file but don't add it to the working set and delete it from the file tree
- [ ] Open a file but don't add it to the working set and delete it from Finder/Explorer
- [ ] Open an image to the working set and delete it from the file tree
- [ ] Open an image to the working set and delete it from Finder/Explorer
- [ ] Open an image but don't add it to the working set and delete it from the file tree
- [ ] Open an image but don't add it to the working set and delete it from Finder/Explorer
Nit: trailing whitespace (this would normally be a JSLint warning... not sure why Travis isn't complaining)