bump minimum Node version to 5 and update node-sass to 3.6.0 so it wo…

…rks somewhat with Node 6

ESLint is still broken, however

Node 4 is getting dated (relatively speaking).

.travis.yml

@@ -1,8 +1,7 @@
 sudo: false
 language: node_js
 node_js:
-  - "5"
-  - "4"
+  - 5
 before_script: npm run external-deps
 script:
   - npm run eslint

README.md

@@ -83,7 +83,7 @@ Thinking about contributing to RES? Awesome! We just ask that you follow a few s
 
 First time installation:
 
-1. Install [node.js](http://nodejs.org) (version 4+).
+1. Install [node.js](http://nodejs.org) (version >= 5).
 1. Install [Python 2](https://www.python.org/downloads/) (*not* version 3).
 1. Navigate to your RES folder.
 1. Run `npm install`.

package.json

@@ -89,7 +89,7 @@
     "json-loader": "0.5.4",
     "merge-stream": "1.0.0",
     "mustache-loader": "0.3.1",
-    "node-sass": "3.5.3",
+    "node-sass": "3.6.0",
     "nyc": "6.4.0",
     "postcss-loader": "0.8.2",
     "progress-bar-webpack-plugin": "1.6.0",