title: ng-file-upload file type/size validations with multiple ng-messages
body: <p>Below is my code to show a text box and a button next to it for uploading a file using <code>ng-file-upload</code>. I am trying to show the respective validation error messages like mandatory field,file size limit and acceptable file types. I am able to successfully show the error messages for required field and file size but not for acceptable file types which means </p>
  
  <p><code>&lt;div ng-message="accept"&gt;File format must be {{ vm.fileaccept }}&lt;/div&gt;</code> is not working. I am setting <code>vm.fileaccept</code> in the controller as <code>vm.fileaccept = '.pdf,image/*';</code></p>
  
  <pre><code>&lt;form name="uploadForm" ng-submit="vm.submitFile()" novalidate&gt;
  &lt;div layout="row" flex="100"&gt;
  &lt;div layout="column" flex="95"&gt;
      &lt;md-input-container&gt;
          &lt;input type="text" readonly name="filename"
                 class="form-control" ng-model="vm.filename" required/&gt;
          &lt;div class="errors"
               ng-show="uploadForm.$submitted || uploadForm.filename.$dirty"
               ng-messages="uploadForm.filename.$error"&gt;
              &lt;div ng-message="required"&gt;Required&lt;/div&gt;
          &lt;/div&gt;
          &lt;div class="errors"
               ng-show="uploadForm.file.$error"
               ng-messages="uploadForm.file.$error"&gt;
              &lt;div ng-message="maxSize"&gt;File size cannot exceed 1MB&lt;/div&gt;
              &lt;div ng-message="accept"&gt;File format must be {{ vm.fileaccept }}&lt;/div&gt;
          &lt;/div&gt;
      &lt;/md-input-container&gt;
  &lt;/div&gt;
  &lt;div layout="column" flex="5"&gt;
      &lt;md-input-container&gt;
          &lt;button
                  ngf-select="vm.selectFile($file, $invalidFiles)" ng-model="file"
                  name="file" ngf-accept="vm.fileaccept" ngf-pattern="vm.fileaccept"
                  ngf-min-height="100" ngf-max-size="1MB"&gt;
              &lt;i class="fa fa-folder-open-o"&gt;&lt;/i&gt;&lt;/button&gt;
      &lt;/md-input-container&gt;
  &lt;/div&gt;
  &lt;/div&gt;
  &lt;/form&gt;
  </code></pre>