made rcov rake task work

Rakefile

@@ -14,6 +14,7 @@ end
 RSpec::Core::RakeTask.new(:rcov) do |spec|
   spec.pattern = 'spec/**/*_spec.rb'
   spec.rcov = true
+  spec.rcov_opts = ['--exclude', 'spec']
 end
 
 task :default => [:start, :spec, :stop]

redistat.gemspec

@@ -25,5 +25,6 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'time_ext', '>= 0.2.8'
   
   s.add_development_dependency 'rspec', '>= 2.1.0'
+  s.add_development_dependency 'rcov', '>= 0.9.9'
   s.add_development_dependency 'yard', '>= 0.6.3'
 end