running `rake` loads all files starting with `test_` which is not supposed to also load the helper,
since the helper should be loaded by each test and is not a test itself.
* Bump minitest version.
* Add basic test helper file.
* Use minitest for web server tests.
* Use Minitest for unix socket tests.
* Use Minitest for ThreadPool tests.
* Use Minitest for TCP-Rack tests
* Use Minitest for TCPLogger tests.
* Add missing helper to test helpers.
* Use Minitest for Rack server tests.
* Use Minitest for Rack handler tests.
* Use Minitest for Puma::Server tests.
* Use Minitest for Puma::Server with SSL tests.
* Use Minitest for persisten connections tests.
* Require puma in test_helper file.
* Use minitest for Puma::NullIO tests.
* Remove unnecessary requires on test files.
* Use Minitest for MiniSSL tests.
* Use Minitest for IOBuffer tests.
* Require bundler/setup in Rakefile.
* Use Minitest for HttpParser tests.
* Use Minitest for Puma::Configuration tests.
* Use Minitest for Puma::CLI tests.
* Bump Minitest version for Ruby 2.1 Gemfile.
* Use Minitest for integration tests.
* Use Minitest for Puma::App::Status tests.
* Remove test-unit from Gemfiles.
* Add timeout helper to Minitest::Test.
* Use Minitest for Puma::Binder tests.
* Remove testhelp file.
* Add missing require to Puma::Binder tests.
* Prefer require instead of require_relative.
Because frameworks like rails dependent on rack, if puma truly wants to
be able to reload new code and thus new versions of rails, it has to be
able to reload rack as well.
Having a dependency on rack held by puma prevented that from happening
and so that dependency has been removed.
