Add API v3 endpoint support

Nova API v3 is now by default in Icehouse. This patch aims to add the
ability to create the endpoint or not.

Change-Id: I66c6c9b439f8320cd56b6899d02bbe01b80f7243
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
(cherry picked from commit 00ed6139ec7346b7a1d9f42e94de72901006d089)
Allow configuring the rbd keyring name

Change-Id: I7342ec1337cf86c0e4bc66b1788e65c53b2878ce
(cherry picked from commit cb0b48016a33233abee032bbffa9f9d25bd1119e)
add rbd keyring name to secret.xml template

With Change-Id: I7342ec1337cf86c0e4bc66b1788e65c53b2878ce
a parameter for configuring the rbd keyring name was introduced.
This parameter should be used in the secrets file also.

Change-Id: I9da148f7f2e940f1d4dec73e1df6f283028bcca1