Remove instance usage of registryUI.taghistory

src/tags/tag-history-button.tag

@@ -16,12 +16,12 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 -->
 <tag-history-button>
   <a href="#" title="This will show the history of given tag"
-     onclick="registryUI.taghistory.go('{ opts.image.name }', '{ opts.image.tag }');">
+     onclick="go('{ opts.image.name }', '{ opts.image.tag }');">
     <i class="material-icons">history</i>
   </a>
 
   <script type="text/javascript">
-    registryUI.taghistory.go = function (image, tag) {
+    go = function (image, tag) {
       route('/taghistory/image/' + image + '/tag/' + tag);
     };
   </script>