title: $http is not a function in link functions of directive
body: <p>I am new to angular js and trying to use directives.
  I want to use $http in link function of directive.
  Below is my code</p>
  
  <pre><code>MyApp.directive('appItem', ['$http',function() { 
    return { 
      restrict: 'E', 
      scope: { 
        transaction: '=' 
      }, 
      templateUrl: 'js/directives/appItem.html' ,
  
      link: function($scope, $http, element, attrs) {
              $scope.process = function(trId) {
                 $http({
                      method: 'PATCH',
                      url: 'http://myapp.domain.local/api/v1/items/'+trId+'.json'
                  }).
                 then(function successCallback(response) {
                  console.log(response);
                 });
              }
          }
  
    }
  }]);
  </code></pre>
  
  <p>But it gives me error:</p>
  
  <pre><code>$http is not a function
  </code></pre>