Move files out of the namespace package

Move oslo.log to oslo_log. Since this library has not been released, we
do not need to retain the old interface for compatibility.

bp/drop-namespace-packages

Change-Id: Id8e2312a72af171918fa4d40117ec652018a37bf
Switch to oslo.context

Nuke our copy of context.py and switch over to the
oslo.context library.

Change-Id: I192238c4de8ccc3e740132219a67e22bb45cb8d0
Enhance the README a bit

Change-Id: I0ed8fd97672544a517c01a7a829595ca0e3fe81c
Merge "Enhance the README a bit"