Remove dependencies for protocols; Add method createProtocol.
Update README to latest API.
Merge branch 'protocol-plugin'

* add sip.createProtocol
* change Transport.register - accept instance of sip.Protocol
Rough example of how this could be modified to parse HEP encapsulated packets.
Remove HEP specific protocol; Format code; Update HEP example.
Merge branch 'parse-hep' of https://github.com/gmazovec/sipcore.js

Conflicts:
	example/hep.js
	lib/sip.js