add test-unit to the gemfile

Author: cbeer

Gemfile

@@ -13,6 +13,7 @@ group :test do
   gem 'redcarpet', :platform => :ruby # For fast, Github-like Markdown
   gem 'kramdown', :platform => :jruby # For Markdown without a C compiler
   gem 'rcov', '~> 0.9', :platform => [:ruby_18, :jruby]
+  gem 'test-unit'
   gem 'simplecov', :platform => :ruby_19
   gem 'simplecov-rcov', :platform => :ruby_19
   gem 'sqlite3', :platform => [:ruby, :mswin]