Add spec for Axiom::Types::Object.finalize
Refactor Axiom::Types::Type.includes specs

* Fix some bugs where subject was not called inside an example
* Changed to use implicit subject where possible
Add spec to ensure Axiom::Types::Type.finalize is idempotent
Remove unnecessary text from comment
Add YARD docs for Axiom::Types::Encodable
Refactor Axiom::Types::Encodable to add constraint in small methods

* The ascii and non-ascii compatible constraints are setup by
  different methods.
Change type deep freezing to not be so aggressive

* The code was freezing primitive classes
Update flay, roodi and yardstick thresholds