Urgent: update underscore.string version to production version.

underscore.string change it's version, please update it. it affect many more opensource project.

npm ERR! Error: No compatible version found: underscore.string@'>=2.2.0rc <2.3.0-'
npm ERR! Valid install targets:
npm ERR! ["0.9.2","1.0.0","1.1.3","1.1.4","1.1.5","1.1.6","2.0.0","2.1.0","2.1.1","2.3.0","2.3.1","2.2.0-rc"]