Add rcov rake task

Rakefile

@@ -2,13 +2,18 @@ require 'bundler/gem_tasks'
 
 Dir.glob('lib/tasks/*.rake').each { |r| import r }
 
+require 'rake'
 require 'rcov/rcovtask'
 require 'rspec/core/rake_task'
-RSpec::Core::RakeTask.new(:spec)
-
-task :rcov => ["functional"] do
+desc "Generate code coverage"
+RSpec::Core::RakeTask.new(:rcov) do |t|
+  t.pattern = "./spec/**/*_spec.rb" # don't need this, it's default.
+  t.rcov = true
+  t.rcov_opts = ['--exclude', 'spec', '--exclude', 'gems']
 end
 
+RSpec::Core::RakeTask.new(:spec)
+
 task :clean do
   puts 'Cleaning old coverage.data'
   FileUtils.rm('coverage.data') if(File.exists? 'coverage.data')