Add Salt 2018.3 tests and update test pillar

Change-Id: I91c8894200ff97a6ef8f5e1c0e5829f84e3e2412
diff --git a/.kitchen.yml b/.kitchen.yml
index 12347a1..658fe92 100644
--- a/.kitchen.yml
+++ b/.kitchen.yml
@@ -37,7 +37,7 @@
 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: