Address ICE concerns from reviews. Fixes #44, #46, #47, #61, and some of #52.

Tony: Explain, give example for ICE candidate pool (#46)
Magnus: ICE policy should be overridable by local policy (#52)
Explain ICE gathering phase (#44)
Replace updateIce with setConfiguration
Define behavior of setConfiguration, explain how changing ICE policy works (#47)
Default candidate pool size to zero (#61)
This sounds way to general to me. I don't think we want a wide range of policy - we basically want hide location and don't hide. When in the location hiding mode, the browser does not reveal local or IP of NAT but it can still gather theses so it has them for when the policy changes.