Read an account from the service

[fab7]

As a User
I need a read service
So that I can read a customer account

Details and Assumptions

* It is implemented using the GET method and has a path parameter specifying the id of the account to read. The route should be: GET /accounts/{id}.
* Read should accept an account_id and use Account.find() to find the account.
* It should return a HTTP_404_NOT_FOUND if the account cannot be found.
* If the account is found, it should call the serialize() method on the account instance and return a Python dictionary with a return code of HTTP_200_OK.

Acceptance Criteria

gherkin 
Given a user account `id`
When I request to retrieve the data of that account  
Then I should return the account data and status code of 200_OK. 
Else It should return 404_NOT_FOUND if the account cannot be found.