replace url binding to transports; messaging can explicitly specifiy the transport.
refit RMI code paths with messaging model changes.
get rid of __getattr__ on the transport.
fix docstrings.
Merge pull request #6 from jortel/transport-model-changes

Transport model changes
Merge branch 'gofer-1.0' into proton

Conflicts:
	test/messaging/base.py
pass url and transport into transport tests.