Don't try to regenerate existing ssl certificates

Rerunning stack.sh after some failure unrelated to ssl setup will fail
due to certificates already existing in the CA index. Don't regenerate
them instead. This is a workaround making devstack development easier
rather than something typical user would run into.

Change-Id: Icfd4cb5132c8c9297eb73159e592b7006295184f
Adds xiv_ds8k cinder driver support

To use xiv_ds8k, set the following in localrc:
CINDER_ENABLED_BACKENDS+=,xiv:<volume-type-name>
XIV_DRIVER_VERSION=<version-string>
SAN_IP=<storage-ip-or-hostname>
SAN_LOGIN=<storage-admin-account>
SAN_PASSWORD=<storage-admin-password>
SAN_CLUSTERNAME=<cluster-name>
CONNECTION_TYPE=<connection-type> iscsi|fc
XIV_CHAP=<chap-type> disabled|enabled

Change-Id: I084ad2b2cb8e34c4a8aed77a52e90f9a9739f1f3
Merge "Adds xiv_ds8k cinder driver support"
Merge "Don't try to regenerate existing ssl certificates"