adding some more specs around to_hash
Merge pull request #2464 from opscode/lcg/to-hash-specs

adding some more specs around to_hash
add partial deep merge cache
add more commentary
remove old knockout merge exception

chef 11 has raised an exception on this for nearly 2 years, we
now simply no longer care and don't spend the cycles to check.
provider resolver perf improvement

move the sorting of the providers to after we make the first cut, still
keeps deterministic ordering, but avoids sorting providers we are just
going to throw away.
remove invalid invalidsubtractivemerge specs