* Ruby binding
* use relative regorus crate in ruby instead of a published version, also cargo fmt
* remove unnecessary Cargo.toml, include the top level Cargo.lock in ruby gem
* ruby bindings continued- add eval_rule, fix _json methods, update README.md
also added rubocop-minitest and rubocop-rake, and added more test coverage
* update README.md to include Ruby bindings
Closes#191