add new_books related test case
add view of book register
add method stubs and add link to new_book_path
first implement create action and its test
bundle update
using a2z gem
refactor create function and add get_book_info
add AWS API setting
using AWS API
refactor books_controller#get_book_info

amazonモデルを作成してAPIの利用はそちらに集約させた
refactor books_controller
travis setting
refactor amazon.rb
drop description column from books table
add book_image view and modify to pass rake spec
add unique constraint into books#isbn
modified factorygirl factory
modify uniqueness
change FactoryGirl symbol
change to img.class from img#id