Code cleanup to have only Milestone 1 (= Batch 1) covered

Code cleanup to have only Milestone 1 (= Batch 1) covered:
Users, Bank accounts, Wallets, Transactions, Pay-ins (/card/web only),
Pay-outs (/bankwire only), Transfers.
==========================

GET /pay-ins/:payinid
GET /pay-outs/:id
GET /transfers/:id (impossible de faire les test integrations sans la
contribution immédiate)
GET /users
GET /users/:userId
GET /users/:userId/bank-details
GET /users/:userId/bank-details/:id
GET /wallets/:id/transactions
GET /wallets/:walletId
POST /pay-ins/card/web
POST /pay-outs/bank-wire
POST /transfers/ (impossible de faire les test integrations sans la
contribution immédiate)
POST /users
POST /users/:userId/bank-details
POST /wallets
PUT /users/:userId
PUT /wallets/:walletId