Bump recursive-readdir (facebook#756)

Removes a deprecation warning: npm WARN deprecated minimatch@0.3.0: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue See: jergason/recursive-readdir#39

Author: fson

packages/react-scripts/package.json

@@ -58,7 +58,7 @@
  "postcss-loader": "0.13.0",
  "promise": "7.1.1",
  "react-dev-utils": "^0.2.0",
- "recursive-readdir": "2.0.0",
+ "recursive-readdir": "2.1.0",
  "rimraf": "2.5.4",
  "strip-ansi": "3.0.1",
  "style-loader": "0.13.1",