statsd module for puppet

tries to implement some best practices:
 * use upstream centos packages to install node and npm
 * use npm to install statsd
 * be as generic as possible (use parametrized class)
 * put config in /etc/statsd.js
 * put upstart initscript in /etc/init/statsd.conf , leverage "restart when process dies" feature

dependencies:
 * currently only supports Centos 6 or higher (upstart)
 * the package nodejs-stable-release so that node/npm packages can be installed from the upstream nodejs repos
   (see https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager)

patches welcome!