Add Salt 2018.3 tests

Change-Id: I2e5ede346e21a28cf3fe00446c2a81bc4b16eaf9
diff --git a/.travis.yml b/.travis.yml
index 6d1abb3..b2187c3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,12 +17,16 @@
   - bundle install
 
 env:
-    - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2016.3 SUITE=cluster
-    - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2016.3 SUITE=single
-    - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2017.7 SUITE=cluster
-    - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2017.7 SUITE=single
-#    - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-bionic-salt-2017.7 SUITE=cluster
-#    - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-bionic-salt-2017.7 SUITE=single
+    - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2016.3 SUITE=cluster
+    - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2016.3 SUITE=single
+    - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2017.7 SUITE=cluster
+    - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2017.7 SUITE=single
+    - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2018.3 SUITE=cluster
+    - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2018.3 SUITE=single
+#    - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2017.7 SUITE=cluster
+#    - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2017.7 SUITE=single
+#    - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2018.3 SUITE=cluster
+#    - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2018.3 SUITE=single
 
 before_script:
   - set -o pipefail