Add Answer model
add test for answer model
init Answers controller
small refactor code
add new and create test for AnswerController
add test and code for #edit in AnswerController
add test and code for #update
add test and code for Answer#destroy
add code to answer views
edit show view
first acceptance test
write red User sign_in test
add red test for User model
Generate User model
install devise
devise generate to User model
implement devise