Update Gemfile and Makefile configuration
  - One Gemfile for all formulas tests
  - Update Makefile for OpenStack tests

Fixes: PROD-24408 (PROD:24408)
Change-Id: Iac85717b9abc970bf72ee3233e68faa7dab3369c
diff --git a/Makefile b/Makefile
index d166862..fb69046 100644
--- a/Makefile
+++ b/Makefile
@@ -18,7 +18,11 @@
 JOBS := 1
 endif
 
+ifeq (,$(wildcard ./.kitchen.openstack.yml))
+KITCHEN_LOCAL_YAML?=.kitchen.openstack.yml
+else
 KITCHEN_LOCAL_YAML?=.kitchen.yml
+endif
 KITCHEN_OPTS?="--concurrency=$(JOBS)"
 KITCHEN_OPTS_CREATE?=""
 KITCHEN_OPTS_CONVERGE?=""