Update dependencies to enable Greenkeeper 🌴 (#125)

* chore(package): update dependencies

* Update lockfile

* Add greenkeeper lockfile support

* Fix eslint errors

.eslintrc

@@ -6,6 +6,7 @@
   "rules": {
     "semi": 0,
     "arrow-parens": 0,
-    "comma-dangle": 0
+    "comma-dangle": 0,
+    "function-paren-newline": 0
   }
 }

.travis.yml

@@ -1,17 +1,20 @@
 language: node_js
+cache:
+  directories:
+    - node_modules
 notifications:
   email: false
 node_js:
-  - "4"
-  - "5"
-  - "6"
-  - "7"
   - "8"
-install:
-  - npm i -g npm
-  - npm i
-script:
-  - npm test
+  - "6"
+  - "4"
+before_install:
+  - if [[ `npm -v` != 5* ]]; then npm install -g npm@5; fi
+  - npm install -g greenkeeper-lockfile@1
+before_script:
+  - greenkeeper-lockfile-update
+after_script:
+  - greenkeeper-lockfile-upload
 jobs:
   include:
     - stage: coverage