Add Gemfile
Fix deprecation warning
Add rake as development dependency
Add code highlighting to Readme
More tests for #from_string
Improve regex in #from_string
Fix #valid? not handling lowercase x. Fixes #6
Merge branch 'refs/heads/feature/basics'
Merge branch 'refs/heads/feature/6-last-character-uppercase'
Merge branch 'refs/heads/feature/improve-from_string'