Silence firefox source map errors/warnings.

The webpack source map configuration was causing errors within
Firefox for the source mapping comments (//@ vs. //#).
This change removes those errors.

Author: coderkevin

examples/simple/webpack.config.js

@@ -2,7 +2,7 @@ var path = require( 'path' );
 var webpack = require( 'webpack' );
 
 module.exports = {
-	devtool: 'cheap-module-eval-source-map',
+	devtool: 'cheap-module-source-map',
 	entry: [
 		'webpack-hot-middleware/client',
 		'./index.jsx'