remove development mode from webpack.config template

Author: timelyportfolio

inst/templates/webpack.config.js.txt

@@ -1,7 +1,6 @@
 var path = require('path');
 
 module.exports = {
-    mode: 'development',
     entry: path.join(__dirname, 'srcjs', '${name}.jsx'),
     output: {
         path: path.join(__dirname, '${outputPath}'),