Add default return value for application willFinishLaunchingWithOptions

The return value is necessary to be able to use openURL because this callback is only called if willFinishLaunchingWithOptions and didFinishLaunchingWithOptions return true. See: http://goo.gl/Q0OQBF
Merge pull request #397 from tma/patch-1

Add default return value for application willFinishLaunchingWithOptions