Working on integration Braintree with credit cards

- CreditCardHelper is now more intelligent. If the customer doesn't exist it will create the customer and add the credit card to him
- Braintree customer IDs are specified in the requests now. So, we always know the ID of a customer within Braintree
- Modified Module.php to load extra configuration options required by NmrStoreApi (payment gateway connection configuration options)
- Adding composer's lock file and autoloader