feat(FormController): add $submitted $setSubmitted

allowing <code>$submitted</code> on <code>FormController</code> allows the user more convenience when dealing with ngMessages for example
https://yearofmoo.github.io/ngMessages/
```javascript
angular.module('yolo', ['ngMessages'])
.controller('exampleCtrl', function($scope) { 
    this.model = '';
    $scope.submitted = false;
    $scope.submit = function() {
      $scope.submitted = true;
    };
    $scope.interacted = function(field) {
      return $scope.submitted || field.$dirty;
    };
}
```
```html
<form name="userForm">
  <input name="emailAddress" ng-model="ctrl.model">
  <div 
    ng-messages="userForm.emailAddress.$error" 
    ng-if="interacted(userForm.emailAddress)" 
    ng-messages-include="error-messages"
  ></div>
</form>
``` 

with <code>$submitted</code> would simply be
```javascript
angular.module('yolo', ['ngMessages'])
.controller('exampleCtrl', function($scope) { 
    this.model = '';
}
```
```html
<form name="userForm">
  <input name="emailAddress" ng-model="ctrl.model">
  <div 
    ng-messages="userForm.emailAddress.$error" 
    ng-if="userForm.$submitted || userForm.emailAddress.$dirty" 
    ng-messages-include="error-messages"
  ></div>
</form>
``` 


I can also add <code>.ng-submitted</code> class etc  that would help for styles