Standardize Travis CI build (#49)

* Upgrade scripts submodule to latest version

* Use scripts submodule for downstream triggers

* Use scripts submodule for pushing image

* Remove obsolete local scripts

Author: giorgiosironi

.scripts

@@ -23,11 +23,11 @@ script:
     - .travis/check-vendor-extra-updated.sh
 
 after_success:
-    - .travis/push-image.sh
+    - .scripts/travis/push-image.sh browser
 
 deploy:
     provider: script
-    script: .travis/downstream-environments.sh $TRAVIS_COMMIT
+    script: .scripts/travis/downstream.sh environments "Update browser to $TRAVIS_COMMIT"
     on:
         branch: master