Retrieve a Customer by username/password

* Retrieve customer profile by username/passowrd
* @param username - customer login
* @param password - customer password
* @param onSuccess - invoked if customer with provided credentials was not found
* @param onError - invoked if exception occurred
- (void) getCustomerInfo: (NSString*) username
password: (NSString*) password
onSuccess: (void (^)(CustomerInfo *resp)) onSuccess
onError: (void (^)(NSError *error)) onError;
Calling this function It is equivalent to a make a login with the username/password passed. The success of this function opens a session with the customer returned. To close the session use logout() method.