Add a variable to control keystone token format

This change lets the developer running devstack
control the token format used by keystone through
setting KEYSTONE_TOKEN_FORMAT in their localrc
file.

Change-Id: Ic1265fcb10b8de112891f61d5e07312322148ec2
Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>
diff --git a/lib/keystone b/lib/keystone
index 06920f8..73d82c5 100644
--- a/lib/keystone
+++ b/lib/keystone
@@ -47,6 +47,7 @@
 KEYSTONE_SERVICE_HOST=${KEYSTONE_SERVICE_HOST:-$SERVICE_HOST}
 KEYSTONE_SERVICE_PORT=${KEYSTONE_SERVICE_PORT:-5000}
 KEYSTONE_SERVICE_PROTOCOL=${KEYSTONE_SERVICE_PROTOCOL:-http}
+KEYSTONE_TOKEN_FORMAT=${KEYSTONE_TOKEN_FORMAT:-PKI}
 
 
 # Entry Points
@@ -82,6 +83,7 @@
 
     # Rewrite stock ``keystone.conf``
     iniset $KEYSTONE_CONF DEFAULT admin_token "$SERVICE_TOKEN"
+    iniset $KEYSTONE_CONF signing token_format "$KEYSTONE_TOKEN_FORMAT"
     iniset $KEYSTONE_CONF sql connection "$BASE_SQL_CONN/keystone?charset=utf8"
     iniset $KEYSTONE_CONF ec2 driver "keystone.contrib.ec2.backends.sql.Ec2"
     sed -e "