add wish,borrowed,donated tables
Fix bug for migration.
Refactor.
Add layouts/_header.erb.
Code Refactoring.
Add signup for index.
Add five_random_books_image_tag in WelcomHelper.
Fix display of donated books in user.
Add signout.
Add wish functions for book.
Add donate_again and donated_total functions for book.
Fix bugs for header and user_page.
Fix signin page.
Add stock information for book.
Finished search function in header.
Add request_list tab for user.
Add request_list for user.
Add pending_list for user.
Add confirm_book function for user, and have bugs about db.
Add onhand_list for user.