Support workspace event listeners that will be created/registered on initialization time

Add an <EventListener> section in workspace.xml (or the <Workspace> section of repository.xml), containing custom javax.jcr.observation.EventListener implementations that will be created and registered when the workspace is initialized.

The DTD for this section might look as follows:

<!ELEMENT EventListener (param*)>
<!ATTLIST EventListener class CDATA #REQUIRED
eventTypes CDATA #IMPLIED
absPath CDATA #IMPLIED
isDeep CDATA #IMPLIED
uuid CDATA #IMPLIED
nodeTypeName CDATA #IMPLIED
noLocal CDATA #IMPLIED>

This would allow creating an audit logger that will log all write operations on a workspace.