Modify keystone-paste.ini file on Kilo upgrade

This change will allow Keystone to modify the keystone-paste.ini file
instead of referencing the Base configuration in Kilo upgrade testing. The Base
configuration that pre-dates Kilo will contain XmlBodyMiddleware, which has been removed.

Documentation has been add in the Kilo Release Notes.

https://wiki.openstack.org/wiki/ReleaseNotes/Kilo#Upgrade_Notes_5

Change-Id: Ice45bdd3c1d5a2a8d7dcda05ac895d03a070aaf4
Closes-Bug: #1398833
Fix LB, FW, and VPN references for Neutron post-upgrade in Kilo+

These services have moved to their respective repos and Neutron
config files for Kilo need to reflect that, once Juno gets
upgraded to Kilo. A link to the release note for this is provided
here:

https://wiki.openstack.org/wiki/ReleaseNotes/Kilo#Upgrade_Notes_6

Change-Id: If057c736996f7723f934fc47300dc81c899eb313
Merge "Modify keystone-paste.ini file on Kilo upgrade"