Upgrade gem dependency
Add MIT license to gemspec
Add contributing docs to gemspec
Remove unnecessary installation section from README
Update README to match other gems' style
Remove unnecessary call to Class#inspect from error message
Change Gemfile to use eval_gemfile
Change specs to use new expect syntax
Fix rubocop warnings

* Add rubocop configuration file
Change flog threshold
Change travis config to match axiom-types
Change rspec to run with warnings enabled