Environment check

This environment check will provide the ability to validate the local environment file is locked to versions that actually exist on the chef server.  Just this past Friday we pushed an environment file that was locked to a version that didn't exist on the server and it caused our server to become unresponsive.  We plan to use this to validate our environment file in our CI server prior to automatically pushing the file up.

Let me know if something doesn't look right or if you preferred it did something else but looking around there is nothing out there that has this functionality.