publish docker image with git hash with latest (#16)

diff --git a/tools/travis/publish.sh b/tools/travis/publish.sh
index 78398f9..9e66d40 100755
--- a/tools/travis/publish.sh
+++ b/tools/travis/publish.sh
@@ -40,4 +40,15 @@
 -PdockerRegistry=docker.io \
 -PdockerImagePrefix=${IMAGE_PREFIX} \
 -PdockerImageTag=${IMAGE_TAG}
+
+  # if doing latest also push a tag with the hash commit
+  if [ ${IMAGE_TAG} == "latest" ]; then
+  SHORT_COMMIT=`git rev-parse --short HEAD`
+  TERM=dumb ./gradlew \
+  :core:${RUNTIME}:distDocker \
+  -PdockerRegistry=docker.io \
+  -PdockerImagePrefix=${IMAGE_PREFIX} \
+  -PdockerImageTag=${SHORT_COMMIT}
+  fi
+
 fi