Unsupported option

This patch adds possibility of using unsupported parameter CONFIG_STORAGE_HOST,
which allows Packstack to install Glance and Cinder to separate host.

Change-Id: I71e82356a3c1ccdeaf784706f44535f8126c93fe
Resolves: rhbz#1131866
(cherry picked from commit b26280d8350275173e2dbace58932e7356fab2f4)
Merge "Unsupported option" into icehouse