Add routing for customer
modified:   config/routes.rb
Add sort method for all customer list
modified:   app/models/customer.rb
Add methods for index, create and show customer
new file:   app/controllers/customers_controller.rb
Add reader and writer to controller customer
modified:   app/controllers/customers_controller.rb
Correct typos in controller
modified:   app/controllers/customers_controller.rb
Update route typos
Add field for region before migration
Add seed file, index view for customers
new file:   app/views/customers/index.html.erb
modified:   db/seeds.rb