Remove salt-2016 from .travis.yml

Change-Id: I3e3fd744326fe3278007ada9eda16ca468795246
diff --git a/.travis.yml b/.travis.yml
index 4f3c1f9..a0ac4ef 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,9 +15,6 @@
   - bundle install
 
 env:
-    - PLATFORM=docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2016.3/salt:2018_11_19 SUITE=server-cluster
-    - PLATFORM=docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2016.3/salt:2018_11_19 SUITE=server-plugin-dirs
-    - PLATFORM=docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2016.3/salt:2018_11_19 SUITE=server-single
     - PLATFORM=docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2017.7/salt:2018_11_19 SUITE=server-cluster
     - PLATFORM=docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2017.7/salt:2018_11_19 SUITE=server-plugin-dirs
     - PLATFORM=docker-dev-local.docker.mirantis.net/epcim/salt/saltstack-ubuntu-xenial-salt-2017.7/salt:2018_11_19 SUITE=server-single