the default implementation of CConsoleCommand now always returns integer
exit code.
If for some reason someone does not want application to exit he could
overide run() method to return null or some other non integer value.
Allowed returning integer values as application exit code in
CConsoleCommand actions.
Application will now exit with the given integer values as exit code.
This is better than just exit(1) because onAfterAction event is called
And you can use the return value when doing
Yii::app()->getCommandRunner()->run(...) to run a specific command
inside an other command.
