use config to determine active theme

scripts/webpack.js

@@ -0,0 +1,13 @@
+const path = require('path');
+const child_process = require('child_process');
+
+const heapSize = 4096;
+const webpackPath = path.join('node_modules', 'webpack', 'bin', 'webpack.js');
+
+const params = [
+  '--max_old_space_size=' + heapSize,
+  webpackPath,
+  ...process.argv.slice(2)
+];
+
+child_process.spawn('node', params, { stdio:'inherit' });