FIrst pass implementation

This includes the basic writeup for the gem with requirements, purpose,
and design.  This locks in to the 1.x.x ruby-based less compiler
b/c that what this engine is for.

This includes the basic lib and test boilerplate stuff so behavior can be
added and tested.

This includes the basic engine implementation with unit tests to test
isolated behavior and a system test to verify digesting in Dassets.

I tried to break up the commits into logical chunks, so follow along their
for more detail.