Added handler for application:openURL:sourceApplication:annotation

This is a very minor change, but I thought it'd be useful.

I don't know how many APIs use this, but in order to use the ios facebook api, "application:openURL:sourceApplication:annotation:" needs to be present
in the application delegate because the api needs to parse out the 
url argument internally or something.  
There might be a better way to get around this though.