Add Salt 2018.3 tests

Change-Id: I903335367873aa5cdc4d9acb95a33d36bf4220dc
diff --git a/.travis.yml b/.travis.yml
index 71564cf..c8024aa 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,10 +17,16 @@
   - bundle install
 
 env:
-  - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2016.3 OS_VERSION=pike SUITE=server_cluster
-  - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2016.3 OS_VERSION=pike SUITE=server_single
-  - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2017.7 OS_VERSION=pike SUITE=server_cluster
-  - PLATFORM=epcim/salt-formulas:saltstack-ubuntu-xenial-salt-2017.7 OS_VERSION=pike SUITE=server_single
+  - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2016.3 OS_VERSION=pike SUITE=server-cluster
+  - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2016.3 OS_VERSION=pike SUITE=server-single
+  - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2017.7 OS_VERSION=pike SUITE=server-cluster
+  - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2017.7 OS_VERSION=pike SUITE=server-single
+  - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2018.3 OS_VERSION=pike SUITE=server-cluster
+  - PLATFORM=epcim/salt:saltstack-ubuntu-xenial-salt-2018.3 OS_VERSION=pike SUITE=server-single
+#  - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2017.7 OS_VERSION=pike SUITE=server-cluster
+#  - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2017.7 OS_VERSION=pike SUITE=server-single
+#  - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2018.3 OS_VERSION=pike SUITE=server-cluster
+#  - PLATFORM=epcim/salt:saltstack-ubuntu-bionic-salt-2018.3 OS_VERSION=pike SUITE=server-single
 
 before_script:
   - set -o pipefail