Standardize repository settings

Add missing file types to `.gitattributes`.
Use `node` instead of deprecated `stable` version specifier for Travis.
Set dev tool to `cheap-module-source-map`.

.gitattributes

@@ -14,9 +14,11 @@
 *.js text eol=lf
 *.js.map text eol=lf
 *.json text eol=lf
+*.jsx text eol=lf
 *.md text eol=lf
 *.vert text eol=lf
 *.xml text eol=lf
+*.yml text eol=lf
 
 # Prefer LF for these files
 .editorconfig text eol=lf

.travis.yml

 language: node_js
 node_js:
 - '4.2'
-- 'stable'
+- 'node'
 cache:
   directories:
   - node_modules

webpack.config.js

@@ -16,6 +16,7 @@ module.exports = {
         host: '0.0.0.0',
         port: process.env.PORT || 8601
     },
+    devtool: 'cheap-module-source-map',
     entry: {
         lib: ['react', 'react-dom'],
         gui: './src/index.jsx'