Extract validation function
Add validation to POST and PUT routes
Use object validation on Atm#new calls
WIP validate POST/PUT requests
Atm#validate object
Export revalidatior Schema for modularity
Respond with proper status codes

Update API to respond with `200`, `400`, `404` and `500` status when applicable.

Add route-specific middleware

 - Load document if request includes `:uid` param
 - Validate request body params for POST and PUT requests