Fixup for bad source maps in demo

Author: STRML

webpack.config.js

@@ -3,6 +3,7 @@ module.exports = {
 	output: {
     filename: './dist/react-draggable.js',
     sourceMapFilename: './dist/react-draggable.map',
+    devtoolModuleFilenameTemplate: '../[resource-path]',
     library: 'ReactDraggable',
     libraryTarget: 'umd'
 	},