Renamed sip ua to sip2sip in user agent header

darcs-hash:20090125164852-58252-488a3a9ff13aa22ca5d8087a0ef6d38c9eb090fc
Renamed sip ua in sample config

darcs-hash:20090125164927-58252-242e6a2e518f1c291275a42b8ecbe233f9c87d56