Arvados

I just uploaded 3252-py-sdk-install-docs-wip (6850ef5) for review. A couple of notes about it:

• I moved test dependencies from requirements.txt to setup.py. This lets us reduce duplication by deleting requirements.txt, and makes the tests easier to run (python setup.py test).
• When this is merged, we'll need to make small changes to the Jenkins build script (for the new test process) and the wiki Hacking page. In both cases we'll be making things simpler, so it seems worthwhile.

LGTM