changed to use 3.1 METplus docker image

.travis.yml

@@ -84,8 +84,8 @@ env:
     # The DOCKERHUB_USER_REPO setting ASSUMES your owner_name 
     # in travis ci IS THE SAME as your docker hub user_name,
     # since it is setting it  based on the travis repo slug.
-    - DOCKERHUB_USER_REPO="`dirname ${TRAVIS_REPO_SLUG}| awk '{print tolower($0)}'`/metplus"
-    - DOCKERHUB_USER_TAGNAME=test
+    - DOCKERHUB_USER_REPO=dtcenter/metplus
+    - DOCKERHUB_USER_TAGNAME=3.1
     # set to true to use default settings
     # if set to false, to use DOCKER_USER_* settings, your dockerhub container.
     - DOCKERHUB_USE_DEFAULT=false