Rewrite without using any Berkshelf code

Should just shell out to whatever berks you have installed.

@samdunne still interested? Maybe we can pair on this next week.
@sethvargo @ivey I felt that this was enough "magic" that I should explain it in plain english to you in case you've not seen this before.

This allows you to throw away any method undefined calls when parsing a DSL without allocating a bunch of additional objects to handle long call chains.