Updated to fullcalendar 1.6.2

Bump to latest version released a couple weeks ago. According to the changelog:

```
version 1.6.2 (7/18/13)
	- hiddenDays option (issue 686)
	- bugfix: when eventRender returns false, incorrect stacking of events (issue 762)
	- bugfix: couldn't change event.backgroundImage when calling updateEvent (thx stephenharris)
```