MAINT: Make dockerspawner pip-installable.
MAINT: Add ipython to requrements.txt.

Just installing jupyterhub via `pip install` can't get IPython until 3.0
is released on PyPI.

See https://github.com/jupyter/jupyterhub/issues/92.
Merge pull request #6 from quantopian/deployed

Adds a rudimentary `setup.py` and `version.py` to make it possible to install this in place for development.