Disabling ERXShutdownHook by default

This patch disables the ERXShutdownHook by default.

The reason is, that ERXShutdownHook does not make any sense when you deploy the application in a servlet container:

When stopping a servlet, no shutdownHook notification will be send. If you relay on ERXShutdownHook to stop background tasks/threads, the application will only terminated completely, when you shutdown the whole application server. In real deployment scenarios, this is often not an option.

So, in servlet context, you have to relay on ApplicationWillTerminateNotification  instead. 

In addition, executing static code in a servlet is considered as bad practice, as the code effects of only the current servlet, but all the other servlets running in the same java VM.

To activate the ERXShutdownHook again, you should add 

-Der.extensions.ERXApplication.enableERXShutdownHook=true

to the VM start options.

Regards
    René