add slack notifications and deploy to travis

.travis.yml

@@ -1,6 +1,29 @@
+sudo: required
+
 language: ruby
+
+services:
+  - docker
+
 rvm:
   - 2.5.1
 
 script:
   - bundle exec rubocop
+  - docker build -t bigbluebutton/greenlight:master .
+
+after_script:
+  - docker images
+
+before_deploy:
+  - docker login -u "$REGISTRY_USER" -p "$REGISTRY_PASS"
+
+deploy:
+  provider: script
+  script: docker push bigbluebutton/greenlight:master
+  on:
+    branch: master
+
+notifications:
+  slack:
+    secure: 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