Working rcov Rake task.

Closes #218

Rakefile

@@ -30,9 +30,11 @@ desc "Run the unit and acceptance specs"
 task :spec => ['spec:unit', 'spec:acceptance']
 
 desc 'Performs code coverage on the factory_girl plugin.'
-Rcov::RcovTask.new do |t|
-  t.test_files = FileList['spec/*_spec.rb']
-  t.verbose = true
+RSpec::Core::RakeTask.new(:rcov) do |task|
+  task.pattern = 'spec/**/*_spec.rb'
+  task.rcov = true
+  task.rspec_opts = "--format progress"
+  task.rcov_opts = %{--exclude osx\/objc,spec,gems\/ --aggregate coverage/coverage.data}
 end
 
 desc "Clean files generated by rake tasks"