refactor(ui-sref): support mock-clicks/events with no data

Sorry, I accidentally pushed this to origin using my old angular-ui permissions. Meant to push to my branch.  I figured it would be confusing now to delete the branch because everyone got the notification now ... 

We found this issue in https://github.com/driftyco/ionic/issues/406 - a mock click event has to supply a `which` in the data, or it won't work.

We now inverse the logic to do nothing if `e.which` - or any event property - is the wrong value.  So event data doesn't have to be supplied now. I added a test for this, too.