Fix helper spec definitions
Require ZenTest 4.9.2 because 4.6.2 requires rubygems ~> 1.8

Otherwise Travis fails to bundle install;

Gem::InstallError: ZenTest requires RubyGems version ~> 1.8. Try 'gem update --system' to update RubyGems itself.
An error occurred while installing ZenTest (4.6.2), and Bundler cannot continue.
Make sure that `gem install ZenTest -v '4.6.2'` succeeds before bundling.
Update Radiant::Config > Radiant.detail