test 'devise'
up
add group category
add group_user
add index to group_user
fix 'belong_to' -> 'belongs_to'
add index to group_topics
add index to posts
remove _header.html
update
rewrite application controller
refactor post controller using 'respond_with'
fix has_many ex)has_many :post -> has_many :posts
change relation t[1]-[n]p to gt[1]-[n]p
test
fixture update
add owner_id to groups
update
update
refactor (respond_with)