Added stubs for LmFeaturePing which will hold the XMPP Ping feature. To keep lm-connection.c as clean as possible the XMPP Ping (XEP-0199) code will live in lm-feature-ping.[ch] instead.

Colin Walters
Frederic Crozat
Josh Beam
Martyn Russell
Richard Hult
Ross Burton
Sjoerd Simons
Tim Robbins
Tollef Fog Heen