ci(travis): Adds Greenkeeper lock file updates.

Author: ryasmi

.travis.yml

@@ -2,7 +2,11 @@ language: node_js
 node_js: node
 sudo: false
 
+before_install:
+  - npm install -g greenkeeper-lockfile@1
+
 before_script:
+  - greenkeeper-lockfile-update
   - npm prune
 
 script:
@@ -14,3 +18,4 @@ script:
 after_success:
   - npm prune --production
   - npm run semantic-release
+  - greenkeeper-lockfile-upload