Radiant CMSをインストールしようとしていますが、実行するたびに：
rake db:bootstrap
プロジェクトディレクトリ内で次のようになります。
rake aborted!
RedCloth is not a class
完全なトレースは次のとおりです。
(in /Users/richardjburton/testradiant)
** Invoke db:bootstrap (first_time)
** Invoke db:remigrate (first_time)
** Invoke environment (first_time)
** Execute environment
rake aborted!
RedCloth is not a class
/Users/richardjburton/testradiant/vendor/radiant/vendor/redcloth/lib/redcloth.rb:167
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
/Users/richardjburton/testradiant/vendor/radiant/lib/radiant/initializer.rb:98:in `library_directories'
/Users/richardjburton/testradiant/vendor/radiant/lib/radiant/initializer.rb:134:in `default_load_paths'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/railties/lib/initializer.rb:839:in `initialize'
/Users/richardjburton/testradiant/vendor/radiant/lib/radiant/initializer.rb:21:in `initialize'
/Users/richardjburton/testradiant/vendor/radiant/lib/radiant/initializer.rb:155:in `new'
/Users/richardjburton/testradiant/vendor/radiant/lib/radiant/initializer.rb:155:in `run'
/Users/richardjburton/testradiant/config/environment.rb:12
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:31:in `require'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/activesupport/lib/active_support/dependencies.rb:156:in `require'
/Users/richardjburton/testradiant/vendor/radiant/vendor/rails/railties/lib/tasks/misc.rake:4
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `call'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `execute'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `execute'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:597:in `invoke_with_call_chain'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with_call_chain'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:607:in `invoke_prerequisites'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:604:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:604:in `invoke_prerequisites'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:596:in `invoke_with_call_chain'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with_call_chain'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:607:in `invoke_prerequisites'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:604:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:604:in `invoke_prerequisites'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:596:in `invoke_with_call_chain'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with_call_chain'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:583:in `invoke'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2051:in `invoke_task'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `each'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2023:in `top_level'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2001:in `run'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/lib/rake.rb:1998:in `run'
/Library/Ruby/Gems/1.8/gems/rake-0.8.7/bin/rake:31
/usr/bin/rake:19:in `load'
/usr/bin/rake:19