login after successfully signed up
update routes
assoc User and Tweet
add Tweet validations
update tweets
add before_filter to tweets
fix typo at Tweet validation
remove tweets/index.html.haml
update tweets/index.html.haml

fix tweets/index.html.haml
update style
paste from https://raw.githubusercontent.com/svenfuchs/rails-i18n/master/rails/locale/ja.yml
update tweets#index
update tweets/index.html.haml
update style
update redirect path
update tweets#create
render validation error messages
define Tweet default_scope
render notice at tweets#index
update users/show.html.haml

fix users/show