title: Pressing enter for selection of a dropdown value directly submits form
body: <p>I am working with ui-select, and whenever I press enter to select some searched results, the result is selected and the form directly goes on to submit. I cant figure it out, what is the problem.</p>
  
  <p>Here is the HTML I'm using</p>
  
  <pre><code>&lt;form&gt;
      &lt;div class="form-group"&gt;
          &lt;label class="col-sm-3 control-label"&gt;Address&lt;/label&gt;
          &lt;div class="col-sm-5"&gt;
              &lt;input type="text" ng-model="address.street" class="form-control"  placeholder="e.g. NUST Campus, H-12"&gt;        
              &lt;div class="form_wrapper_error"&gt;
                  &lt;p ng-show='addressError'&gt;{{addressError}}&lt;/p&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
      &lt;div class="form-group"&gt;
          &lt;label class="col-sm-3 control-label"&gt;City/Town&lt;/label&gt;
          &lt;div class="col-sm-5"&gt;
              &lt;!-- &lt;location-autocomplete bind-value="address.city" coordinates="cityAddInitialCoordinates" placeholder="e.g. Islamabad"&gt; --&gt;
              &lt;ui-select ng-model="$parent.address.city"
                  theme="select2"
                  reset-search-input="true"
                  title="Select City"&gt;
                  &lt;ui-select-match allow-clear="true" placeholder="Select City"&gt;{{$select.selected}}&lt;/ui-select-match&gt;
                  &lt;ui-select-choices repeat="city as city in cities track by $index"
                      refresh="refreshLocation($select.search)"
                      refresh-delay="0"&gt;
                      &lt;div ng-bind-html="city | highlight: $select.search"&gt;&lt;/div&gt;
                  &lt;/ui-select-choices&gt;
              &lt;/ui-select&gt;
              &lt;div class="form_wrapper_error"&gt;
                  &lt;p ng-show='cityError'&gt;{{cityError}}&lt;/p&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
      &lt;div class="form-group"&gt;
          &lt;label class="col-sm-3 control-label"&gt;Zip&lt;/label&gt;
          &lt;div class="col-sm-5"&gt;
              &lt;input type="text"  ng-model="address.zip" class="form-control"  placeholder="e.g. 44000"&gt;
              &lt;div class="form_wrapper_error"&gt;
                  &lt;p ng-show='zipError'&gt;{{zipError}}&lt;/p&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
      &lt;div class="form-group"&gt;
          &lt;div class="col-sm-8"&gt;
              &lt;button class="btn btn-primary buttt" ng-click="addAddress()"&gt;Add Address&lt;/button&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/form&gt;
  </code></pre>