修正 coding style 錯誤
Merge pull request #6 from sdlong/t12088

加入使用者機制
generate migrate create_group_user and model group_user
rake db:migrate create_group_user
setting user and group 多對多資料庫關聯
User 必須是社團成員才能發表文章
generate quit and join group in models/user.rb
generate quit and join in groups_controller
generate quit and join group in models/user.rb
generate quit and join in views/groups/show
User is member of group that create himself
如果不是 group 創辦人，就不會顯示 edit group 按鈕
Merge pull request #7 from sdlong/t12089

實作簡單的 Account 後台機制
generate controller account/groups and posts without blank helper , scss, js
個人帳戶後台基本設定完成 (空白 index)
account/groups/index done
account/posts/index done
post 的排列要以 最新 => 最舊 順序排列
migrate add_posts_count_to_group
migrate add_posts_count_to_group