Module author: Sylvain Hellegouarch <sh@defuze.org>
Decorator to wrap a callable so that it can be used as a XMPP handler by the headstock client.
It will set various attributes to the wrapped callable:
name XMPP stanza name
ns XMPP stanza namespace
once False - flag indicating if the handler should be called only once and unregistered automatically
forget True - flag indicating if the dispatched bridge.Element instance should be automatically forgotten once dispatched.