Moved stun_servers setting to ice settings group

Ignore-this: 3fde3fe0d51566e8aa022ceba16483dd

darcs-hash:20090609094818-1e3d8-2c295fb169bfa967adee375674a30b9d9319a8f6
Removed Account.registration.use_stun setting

Ignore-this: f31c9338e450ddadb9fc6ba0b0deac25

darcs-hash:20090609094946-1e3d8-12e0683596f89da590309f0b02d7275b67fe799c