Add Salt 2018.3 tests

Change-Id: I087bd1f1e5ec17c2e98bfb579f9de0e513a65811
diff --git a/.kitchen.yml b/.kitchen.yml
index ca1e26e..8695bac 100644
--- a/.kitchen.yml
+++ b/.kitchen.yml
@@ -36,7 +36,7 @@
 platforms:
   - name: <%=ENV['PLATFORM'] ||  'saltstack-ubuntu-xenial-salt-stable' %>
     driver_config:
-      image: <%=ENV['PLATFORM'] || 'epcim/salt-formulas:saltstack-ubuntu-xenial-salt-stable'%>
+      image: <%=ENV['PLATFORM'] || 'epcim/salt:saltstack-ubuntu-xenial-salt-stable'%>
       platform: ubuntu
 
 suites: