[fixed] demos server

Summary: Pundle apparently doesn't resolve ES modules, so it's using CommonJS.  Rollup needs ES modules, so they are what the main `tsconfig` generates.

Reviewers: O2 Material Motion, O3 Material JavaScript platform reviewers, #material_motion

Tags: #material_motion

Differential Revision: http://codereview.cc/D3507

Author: appsforartists

packages/demos-react/.pundle.js

@@ -46,7 +46,10 @@ module.exports = {
             compilerOptions: Object.assign(
               {},
               mainTSConfig.compilerOptions,
-              tsConfig.compilerOptions
+              tsConfig.compilerOptions,
+              {
+                module: 'commonjs',
+              }
             )
           }
         }