make salt-api port string

Change-Id: I348a1e5d51a6ff63ab28c4535a525297efbd8900
diff --git a/lab-pipeline.groovy b/lab-pipeline.groovy
index 268e9e8..c69f364 100644
--- a/lab-pipeline.groovy
+++ b/lab-pipeline.groovy
@@ -100,9 +100,9 @@
                     currentBuild.description = "${HEAT_STACK_NAME}: ${saltMasterHost}"
 
                     if (INSTALL.toLowerCase().contains('kvm')) {
-                        saltPort = 8088
+                        saltPort = '8088'
                     } else {
-                        saltPort = 8000
+                        saltPort = '8000'
                     }
 
                     SALT_MASTER_URL = "http://${saltMasterHost}:saltPort"