Add RSpec in Gemfile

`bundle install`
`rails generate rspec:install`

Fix .rspec
`--color --format documentation`
Add validation in app/models/user.rb
Add test file for balidation

バリデーション用のテストコードの記述
	new file:   spec/models/user_spec.rb
Add capybara, turnip in Gemfile

`bundle install`

fix .rspec
`-r turnip/rspec --color --format documentation`
Fix to run Turnip
Add feature, step file

`rake db:test:clone` before `rspec`