use bundle-collapser to reduce browserified file size

PR #2792 

// v0.13.0-alpha.1

 file | before | after | reduced percentage
 ---- | ------ | ----- | ------------------
 react.min.js | 134656 | 116478 | 13.5%
 react-with-addons.min.js | 146071 | 126510 | 13.4%

grunt test all passed and didn't create any linter errors.