Explicitly include the service URL in stream links from the annotation card

Make these links work when the app is hosted at a different
base URL from the Hypothesis service.

h/templates/client/annotation.html

@@ -106,7 +106,7 @@
        ng-if="(vm.canCollapseBody || vm.form.tags.length) && !vm.editing()">
     <ul class="tag-list">
       <li class="tag-item" ng-repeat="tag in vm.form.tags">
-        <a href="/stream?q=tag:'{{tag.text|urlencode}}'" target="_blank">{{tag.text}}</a>
+        <a href="{{::vm.serviceUrl}}stream?q=tag:'{{tag.text|urlencode}}'" target="_blank">{{tag.text}}</a>
       </li>
     </ul>
     <div class="u-stretch"></div>