Changed default value for account.nat_traversal.enable_ice to False

Ignore-this: 8f5002f2a2b63eec27f95f82a6b0af2a

darcs-hash:20091118130014-1e3d8-b8ad253fb4dbe62fc07a0e068f81d2ed4fc35f8f
Disabled echo cancellation in the alert conference bridge

Ignore-this: aed9e7ed7f5a2ef68792ef680d98f852

darcs-hash:20091119144416-1e3d8-6e4973dda25e19c23721bd6b671b114c79fb1d47