Clean up indentation, remove whitespace
Rework test suite and dependencies

- Move from test/unit to minitest
- Add required gem not in Gemfile yet: mocha
- Remove unused gems: activesupport, ruby-debug, shoulda-matchers
- Remove superfluous gems: shoulda
Clean up gem packaging

- gemspecs don’t need separate maintenance these days
- pushing gems is as easy as “gem push”
- provide a dynamic gemspec
- quiet tests and show our pride in a clean test run!
Require rdoc/task
Use bundler's gem tasks
Use Rake's clobber task to remove rdoc/ and pkg/

rdoc/task automatically clobbers the generated RDoc HTML files.
No need to describe the test task (done automatically)
Add rdoc/ to gitignore
Merge pull request #45 from TheClymb/master

Modernize gem