Fixed xcap_rls_services to not prepend sip: if input already contains it

Ignore-this: bf4288bdd03081509546ddd44361cdbc

darcs-hash:20090520063959-1e3d8-98d3d9f343fc03deab09ce1419ba3c9d834db09b
Removed unused import in sip_subscribe_xcap_diff

Ignore-this: 9320d0d4c882f5f0ea83c1d4d43341ed

darcs-hash:20090520064046-1e3d8-b6795a005842a648dc5c09b146539733fe04d36a