Passion the correct branch to docker cloud

.travis/docker.sh

@@ -9,7 +9,7 @@ if [[ $TRAVIS_TAG ]]
  then
   CURL_DATA='{"source_type":"Tag","source_name":"'"$TRAVIS_TAG"'"}';
 else
-  CURL_DATA='{"source_type":"Branch","source_name":"develop"}';
+  CURL_DATA='{"source_type":"Branch","source_name":"'"$TRAVIS_BRANCH"'"}';
 fi
 
 curl -H "Content-Type: application/json" --data "$CURL_DATA" -X POST "$CURL_URL"