Passing context data through RPC headers
Lower level implementation with custom WorkerContext
flakes caused by a doc-test like doc string
Header decoding/encoding now happening on providers. Keys still specified by WorkerContext
unit tests for header encoder/decoder
Addressing code review
Merge branch 'share-worker-context-data' of https://github.com/onefinestay/nameko into share-worker-context-data

Conflicts:
	nameko/service.py
tidyup
Merge remote-tracking branch 'origin/evolutionary' into share-worker-context-data

Conflicts:
	nameko/messaging.py
	nameko/rpc.py
	test/conftest.py
	test/test_rpc.py
removed duplicate inheritence
pyflakes
Merge pull request #54 from onefinestay/share-worker-context-data

Share worker context data