Add register method.
Revert version number change
Add the basic scaffolding for the register command and a
register_no_auth method
We don't need to raise for a nil user
Modify the XML creation flow for register for better code reuse
Add method for authentication
Use specified domains for register
Merge all register helper methods into a single #parse_user method
Make user-agent a constant
Fix Contact field in sends
Add node name to Contact
Make a TODO for possible SIPS support
Merge pull request #16 from wdrexler/feature/register

Add REGISTER support