Add ng-click and button type to scope filtering

* This addition gives the user an ability to specify a submit function
  so that it can be used as a normal button that does an action — may be
  update some attribute by fetching data from the server — and not just
  a form submit. This will make it act more like a normal HTML button.

* The button type can be set which gets parsed as a string.
Interesting. I wouldn't have guessed that. Thanks for pointing out.