Format calendar header to show month and year when looking at months in previews/next years.

Author: g1eb

src/datetime-range.html

@@ -36,7 +36,7 @@
         scroll-up="calendar.add(1, 'months')"
         scroll-down="calendar.subtract(1, 'months')">
         <div class="arrow arrow-left" ng-click="calendar.subtract(1, 'months')"></div>
-        <span ng-bind="calendar.format('MMMM')"></span>
+        <span ng-bind="calendar.format('YYYY') === current.format('YYYY') ? calendar.format('MMMM') : calendar.format('MMMM YYYY')"></span>
         <div class="arrow arrow-right" ng-click="calendar.add(1, 'months')"></div>
       </div>
       <div class="calendar-body">