refs #181 don't display all draft blogs
refs #181 add validation test for mail form
refs #141 add 'simplecov' that a code coverage analysis tool for Ruby, to Gemfile
refs #141 ignore the folder of 'simplecov'
refs #141 set to use 'simplecov'
refs #181 edit the test to create the draft blogs
refs #241 add functions to create blogs
refs #181 add validation rule to blog comments
refs #221 'rails generate model user provider uid name screen_name image'
refs #221 create the twitter users, and log in the user accounts
refs #221 'rails generate migration AddParentIdToUser parent_id:integer'
refs #221 'rails generate migration AddTypeToUser type:string'
refs #221 'rake db:migrate' & 'rake db:migrate RAILS_ENV=test'
refs #221 login and logout by the twitter omniauth on the page
refs #181 update blogs on the admin page
refs #221 'rails generate migration AddAdminToUser admin:boolean'
refs #221 'rake db:migrate' and 'rake db:migrate RAILS_ENV=test'
refs #261 'rails generate mailer notifier create_blog'
refs #261 send mail by 'Notifier.create_blog.deliver'