fix: add before_deploy step to travis

Author: germanattanasio

.travis.yml

@@ -16,6 +16,7 @@ env:
   - BX_API=https://api.ng.bluemix.net
   - BX_ORGANIZATION=WatsonPlatformServices
   - BX_SPACE=demos
+before_deploy: npm install -g bx-blue-green
 deploy:
 - provider: script
   skip_cleanup: true
@@ -28,4 +29,4 @@ deploy:
   skip_cleanup: true
   script: npx semantic-release
   on:
-    node: 8
+    node: 8