fix Event.__unicode__() method 

Perhaps i misunderstand the original intent of that method, but rendering a date with 'l, DATEFORMAT' as the format creates a weird string like "My Event: Wednesday, WedPMCDTMay_May-0500RMayPMCDT-Wednesday, WedPMCDTMay_May-0500RMayPMCDT" so i changed it so it will render like "MyEvent: May 22, 2013 - May 22, 2013" instead.
Merge pull request #10 from smcoll/patch-6

fix Event.__unicode__() method