BZ #1123301 - nova-metadata VIP/listener is missing on port 8775 in haproxy.cfg

https://bugzilla.redhat.com/show_bug.cgi?id=1123301

This was already in the puppet, but had been disabled for a previous release.
This patch re-enables it to see if it now works as expected.
BZ #1123301 - add metadata_listen param

https://bugzilla.redhat.com/show_bug.cgi?id=1123301

Otherwise openstack-nova-api attempts to listen on 0.0.0.0,
causing the error:

ERROR nova.wsgi [-] Could not bind to 0.0.0.0:8775
CRITICAL nova [-] error: [Errno 98] Address already in use

(cherry picked from commit 73a342aeabb03d66d7a26e508183c90ddf72f468)
Merge pull request #336 from jguiditta/bz1123301-nova-metadata-haproxy

Bz1123301 nova metadata haproxy