title: Breaking a form between multiple tabs in angular breaks validation
body: <p>I have an angular form spitted between several tabs with angular UI directive.</p>
  
  <pre><code>&lt;form name="campaignForm" class="form-horizontal" novalidate &gt;
  &lt;input type="text" name="title" class="input-xxlarge" placeholder="Campaign title" ng-model="campaign.title" required&gt;
    &lt;span ng-show="campaignForm.title.$error.required" class="help-inline"&gt;
        Required&lt;/span&gt;
  
  &lt;tabset&gt;
  &lt;tab&gt;
  &lt;/tab&gt;
  &lt;input type="email" name="emailFrom" class="input-xsmall" placeholder="From email address" ng-model="campaign.info.emailFrom" required="" /&gt;
        &lt;span ng-show="campaignForm.emailFrom.$error.required" class="help-inline"&gt;
            Required&lt;/span&gt;
  &lt;tab&gt;
  &lt;input type="text" name="emailSubject" class="input-xxlarge" ng-model="campaign.info.emailSubject" placeholder="Please enter email subject" required/&gt;
  &lt;span ng-show="campaignForm.emailSubject.$error.required" class="help-inline"&gt;
                Required&lt;/span&gt;
  &lt;/tab&gt;
  &lt;/tabset&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>Please <a href="http://plnkr.co/edit/TbTBw28dhWWjRs0C1THx?p=preview">see my Plunker</a>.</p>
  
  <p>As you can see, only the input outside tabs directive works. The other inputs validation doesn't work because TABS create scopes. Any ideas how to solve this issue?</p>