fix(datepicker): remove unecessery </th> from a template

Closes angular-ui#1119

Author: pkozlowski-opensource

template/datepicker/datepicker.html

@@ -7,7 +7,7 @@
           <span class="glyphicon glyphicon-chevron-left"> </span> 
         </button>
       </th>
-      <th colspan="{{rows[0].length - 2 + showWeekNumbers}}"><button type="button" class="btn btn-md btn-link btn-block" ng-click="toggleMode()"><strong>{{title}}</strong></button></th></th>
+      <th colspan="{{rows[0].length - 2 + showWeekNumbers}}"><button type="button" class="btn btn-md btn-link btn-block" ng-click="toggleMode()"><strong>{{title}}</strong></button></th>
       <th style="overflow: hidden; min-width: 26px">
         <button type="button" class="btn btn-xs btn-link" ng-click="move(1)"> 
           <span class="glyphicon glyphicon-chevron-right"> </span>