Migrate to oslo.context

The oslo.context lib version 0.1.0 has been just release and we
could migrate to it now.

Change-Id: Id2e23b0f1e42b1addf97f0b7fe08fb00fe5d17dd
Use xml.dom.minidom and xmlutils in unit tests

This is an example using xml parsing in existing unit
tests instead of assertIn and string comparisons to verify
workflow generation.  It's much less fragile.

If folks like this, we can change other tests similarly.

Change-Id: Ib1c266933a4a3104af34586527148c2612019000
Merge "Migrate to oslo.context"
Merge "Use xml.dom.minidom and xmlutils in unit tests"