Wix: external server management in gateways manager, SàT: bug fixes in gateway management - SàT: from twisted.words.protocols.jabber.error module imported as jab_error to avoir name colision with error log method - XEP_0100 plugin: added errback for disco info - XEP_0077 plugin: registration callback now look for "x" element (data form: see XEP-0004), and send an error message if it can't find it. - Wix: added fields for browsing external server gateways