Code signing fixes after Xcode update to 6.1.
Refine Swift usage by using constructor for current NSDate.
Update Swift enums usage per Swift 1.1 (Xcode 6.1).
Refine Swift usage by using constructor for NSError.
Properly override back bar-button-item with lazy property.
Update per specific Swift dictionary interface type change.
Update Swift options usage per framework interface changes.

Yet again, time to play optionals whack-a-mole.
Note again the possibility of method signatures
that are outdated but not generating warnings.
Fix event validation regression.