title: angularjs disable button on $http/$q calls
body: <p>following the DRY principal, i want to write a button directive which keeps button disabled for the duration of $http class.</p>
  
  <p>I want to do this so as to forbid user from clicking the buttons multiple times, but i am not able to think on how to get function promise status inside a directive, given that the function resides on $scope</p>
  
  <p>the scenario is very generic, buttons ng-click does call a function which in turn makes $http calls. on user click : button should get disabled and should be enabled only after the $http call is resolved, either success or failure. </p>