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

Sorry, I accidentally pushed this to origin using my old angular-ui permissions. I meant to push to my fork.  I figured it would be confusing now to delete the branch here because everyone got the notification now ... 

This problem is found in an issue at https://github.com/driftyco/ionic/issues/406 - a mock click event has to supply a `which` in the data, or ui-sref won't work.

This now inverses 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.