Isolate creating service users

The code for creating service users is almost exactly the same. Abstract
this into a function that can be reused and standardized.

Change-Id: I3a4edbff0a928da7ef9b0097a5a8d508fdfab7ff
diff --git a/lib/ceilometer b/lib/ceilometer
index f1617fb..f03bab2 100644
--- a/lib/ceilometer
+++ b/lib/ceilometer
@@ -105,13 +105,10 @@
 # SERVICE_TENANT_NAME  ceilometer   ResellerAdmin (if Swift is enabled)
 function create_ceilometer_accounts {
 
-    local service_tenant=$(openstack project list | awk "/ $SERVICE_TENANT_NAME / { print \$2 }")
-    local admin_role=$(openstack role list | awk "/ admin / { print \$2 }")
-
     # Ceilometer
     if [[ "$ENABLED_SERVICES" =~ "ceilometer-api" ]]; then
-        local ceilometer_user=$(get_or_create_user "ceilometer" "$SERVICE_PASSWORD")
-        get_or_add_user_role $admin_role $ceilometer_user $service_tenant
+
+        create_service_user "ceilometer" "admin"
 
         if [[ "$KEYSTONE_CATALOG_BACKEND" = 'sql' ]]; then
             local ceilometer_service=$(get_or_create_service "ceilometer" \