Merge pull request #10 from sue445/feature/cmd_option

guardが動いていなかったのを修正

Author: joker1007

Guardfile

@@ -1,6 +1,6 @@
 
 
-guard 'rspec' do
+guard 'rspec', cmd: 'bundle exec rspec' do
   watch(%r{^spec/.+_spec\.rb$})
   watch(%r{^lib/(.+)\.rb$})     { |m| "spec/lib/#{m[1]}_spec.rb" }
   watch('spec/spec_helper.rb')  { "spec" }