Updates ZenTest to support rubygems 2.1

Author: alindeman

rspec-rails.gemspec

@@ -37,6 +37,6 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rake',     '~> 10.0.0'
   s.add_development_dependency 'cucumber', '~> 1.3.5'
   s.add_development_dependency 'aruba',    '~> 0.4.11'
-  s.add_development_dependency 'ZenTest',  '4.9.0'
+  s.add_development_dependency 'ZenTest',  '4.9.4'
   s.add_development_dependency 'ammeter',  '0.2.5'
 end