src/SIP.js: fix indentation
Most modules export themselves instead of setting SIP.*

SIPMessage and Session are omitted because they set multiple SIP.*
Split SIPMessage into OutgoingRequest, Incoming{Message, Request, Response}
Split Session.js into Session/{Constants, Session, InviteServerContext, InviteClientContext}.js
EventEmitter: require('./LoggerFactory') instead of injecting SIP