for adding the rspec mock
removed user_id from presence validation as it will get to nil
removed customer_id from presence validation
minor changings
updated factories for credit_card and transaction
good number of specs for, create_transaction, transaction_with_vault, creating customer on braintree and creating the subscription
update the mocking framework
added subscription_id in factory
specs for cancel_subscription in service
added specs for update_braintree_credit_card info
specs for private methods
make the method to private