Added some instructions for using io.js in place of node.
Added some instructions for using io.js in place of node.

Lajt/vagrant-node-env,renobit/vagrant-node-env,carl-parrish/vagrant-node-env,renobit/vagrant-node-env,carl-parrish/vagrant-node-env,Lajt/vagrant-node-env,carl-parrish/vagrant-node-env,renobit/vagrant-node-env,Lajt/vagrant-node-env