Use oslo.sphinx and remove local copy of doc theme

Use the new oslo.sphinx version of the OpenStack doc
theme instead of copying it into this repo.

blueprint oslo.sphinx

Change-Id: I0bd91f7bb43f97b99051fed65b75fc05d5149cc8
Hook docstrings into the published docs

Fixes bug #1182842

We've always had pretty decent documentation coverage in the docstrings
but have never taken the time to hook them into the published docs.

This is a first-cut at doing that. There's plenty of rough edges, but
it's a good start.

Change-Id: I62a509e7d6e156e9b67e75bef9da68fbfc4601ac