mod_pubsub_subscription: Match stanzas with fixed prefix only This should help filter out any other unrelated iq stanzas which may be exchanged with the pubsub service. For example, a separate module was requesting the item list from a subscribed node, but this module was incorrectly attempting to handle the result.

This module produces more detailed HTTP logs for Prosodys built-in HTTP
server. The format is similar to that of Apache and go into Prosodys
normal logs at the `info` level.