Major performance improvements to the Dashboard and Calendar views

* Close the PHP session for writing as early as possible in most AJAX
  calls for those views
* Reduce the number of roundtrips to the server in both the Dashboard
  and Calendar views by putting the data in our HTML response (this
  makes a massive difference)
* Eliminated a couple of unneccessary AJAX calls
* Use lazy loading in full calendar
* Fixed a bug in the week view that only occurs near the end of the
  week (date->gmdate bug!)

airtime_mvc/public/js/airtime/schedule/schedule.js

@@ -312,7 +312,7 @@ function createFullCalendar(data){
         ],
         contentHeight: mainHeight,
         theme: true,
-        lazyFetching: false,
+        lazyFetching: true,
         serverTimestamp: parseInt(data.calendarInit.timestamp, 10),
         serverTimezoneOffset: parseInt(data.calendarInit.timezoneOffset, 10),