devstack (stack.sh) fails when extra config files are specified

Latest merge of https://review.openstack.org/#/c/71996/ exposes an issue
in stack.sh which did not surface before.

Please see the details of the issue in the bug description.

Closes bug: 1285884

Change-Id: Ie231c9835497c2a418a61d339dfd5df1aab9e3d7
Remove bm_poseur, unmaintained and obsolete

The bm_poseur git repository link has been broken
for over 11 months. The virtualized/fake baremetal
environment is not working and has not worked in a
long time. Now, on the tail of enabling 'enable -o errexit',
this functionality now has a hard break.

Change-Id: I3cbd8db58c422bc5273d2433278aaa5e449ecfd9
Closes-Bug: 1285954
Add configurations for the OpenFlow Agent mechanism driver

This patch supports configurations for an environment of the OpenFlow Agent mechanism driver
Set the following variables in a localrc to be ran this mechanism driver.

Q_ML2_PLUGIN_MECHANISM_DRIVERS=ofagent
Q_AGENT=ofagent

Implements: blueprint ryu-ml2-driver
Change-Id: I774da9a26f241487dfa4ec124b12f528704d860b
Merge "Remove bm_poseur, unmaintained and obsolete"
Merge "Add configurations for the OpenFlow Agent mechanism driver"
Merge "devstack (stack.sh) fails when extra config files are specified"
Merge branch 'master' of github.com:openstack-dev/devstack