Display release date in Updater and Packagemanager

Task-number: QTIFW-25

Change-Id: I8c4d4ac3983b40afd3072fa36dec348b9c67f1d0
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>