Use the python implementation of instack-install-undercloud
Use the python implementation of instack-install-undercloud

We currently shell out to call the instack-install-undercloud bash script,
however this script now just runs the python implementation. This patch
cuts out the bash middleman.

Change-Id: I326fb8638c803b8f05fe531555056911ef9568c8

openstack/python-tripleoclient,rdo-management/python-rdomanager-oscplugin