(QENG-515) Provide Important Env Vars Set in Debug Output

This provides the Environment Variables that are pertinent to running
Beaker as an error message after a failed run or as a debug message
on a successful run in the debug log level.

This requires PR #244
Let's get some yard docs on this.  Also, how are these env vars 'important'?  Looks like a combination of beaker supported env vars, pathing and versions.  So, maybe print_current_env or some such?