Cinder: Set os_privileged_user credentials (for os-assisted-snapshots)

When calling os-assisted-snapshots APIs, Cinder often (by default) needs
 to pass an admin token to Nova. Currently it uses the credentials of
 the current user.

This will cause calls to Nova APIs for assisted volume snapshots to fail.

Configuration options should be added to specify different credentials
for talking to Nova.

Change-Id: I9e3ed53f4e1349d57a0c33518445f54ac63e36ec
Related-Bug: #1308736

Author: Jordan Pittier

lib/cinder

@@ -299,6 +299,11 @@ function configure_cinder {
         iniset $CINDER_CONF DEFAULT ssl_key_file "$CINDER_SSL_KEY"
     fi
 
+    # Set os_privileged_user credentials (used for os-assisted-snapshots)
+    iniset $CINDER_CONF DEFAULT os_privileged_user_name nova
+    iniset $CINDER_CONF DEFAULT os_privileged_user_password "$SERVICE_PASSWORD"
+    iniset $CINDER_CONF DEFAULT os_privileged_user_tenant "$SERVICE_TENANT_NAME"
+
 }
 
 # create_cinder_accounts() - Set up common required cinder accounts