Run npm install instead of npm ci in Travis because npm ci doesn't nice with greenkeeper changes

Author: 1999

.travis.yml

@@ -13,6 +13,7 @@ addons:
     - gcc-4.8
     - g++-4.8
 before_install: npm install -g greenkeeper-lockfile
+install: npm install
 before_script: greenkeeper-lockfile-update
 after_script: greenkeeper-lockfile-upload
 script: npm run test:ci