Separate release and deploy stages

Stage jobs are run in parallel and we don't want as helm needs the
docker image to be pushed. Furthermore Travis does not run any stage job
if a job from the previous stage has failed which is exactly what we
want.

Signed-off-by: Rafael Porres Molina <rafa@sourced.tech>

.travis.yml

@@ -7,6 +7,8 @@ stages:
   - name: test
   - name: release
     if: tag IS present
+  - name: deploy
+    if: tag IS present
 
 go_import_path: github.com/src-d/lookout-gometalint-analyzer
 
@@ -54,7 +56,7 @@ jobs:
         - PKG_OS=linux make packages
         - DOCKER_PUSH_LATEST=true make docker-push
     - name: 'Deploy to staging'
-      stage: release
+      stage: deploy
       install:
         - make install-helm
       script: