Standardize repository settings

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

.gitattributes

@@ -17,6 +17,7 @@
 *.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

@@ -1,7 +1,7 @@
 language: node_js
 node_js:
 - "4.2"
-- "stable"
+- "node"
 sudo: false
 cache:
   directories:

webpack.config.js

@@ -8,7 +8,7 @@ const base = {
         host: '0.0.0.0',
         port: process.env.PORT || 8361
     },
-    devtool: 'source-map',
+    devtool: 'cheap-module-source-map',
     module: {
         rules: [
             {