chore(greenkeeper): support for lockfiles (#510)

Author: dhruvdutt

.travis.yml

@@ -49,7 +49,7 @@ install:
   - npm ci
   - npm install -g codecov
   - npm install -g eslint
-  - npm install -g greenkeeper-lockfile@1
+  - npm install -g greenkeeper-lockfile@2
   - lerna bootstrap
 
 before_script: greenkeeper-lockfile-update
@@ -62,6 +62,6 @@ jobs:
     - stage: NPM release
       if: branch = master
       node_js: "lts/*"
-      script: 
+      script:
         - npm run changelog
         - npm run travis-deploy-once "npm run semantic-release"