Formatting Refactor Discussion

## Objective
Reduce the scope of the database wrapper to interacting with the database.

## Proposal
Require that all Entities have a validator and formatter class attached. By updating this class, we can make our error checking extensible and move most of the logic out of the ``database_wrapper.py`` file.

We have a top level initialization static method on each class called ``from_dict(data)``. All of the validation/formatting code in the ``database_wrapper`` could be reduced to the following:
```
try:
entity = entity_type.from_dict(data)
except:
#Handle errors
#Perform insert/update/delete
```

Internally this method would incorporate the following:

```
validator = EntityTypeValidator()
formatter = EntityTypeFormatter()
validator.validate(data) #Checks data for critical errors, raises exceptions handled above.
formatted_data = formatter.format(data) #Casts data to correct type and fills in missing replaceable fields.
entity = EnitityType()
for key in formatted_data:
setattr(entity, key, formatted_data[key])
return entity
```

Examples of validators and formatters can be found the the ``./modules`` folder.

## Benefits
- Upholds single responsibility principle: database_wrapper is focused on interacting with database. Formatters format. Validators validate
- Extensible: allows formatting and validating to be abstracted from the wrapper, so adding new features doesn't mean pushing breaking changes.
- Modularized: Allows code to be divided into different files, making the codebase more readable.
- More performant? We're loading k/v pairs for specific use cases every time we init the server. If this were abstracted, we wouldn't have to load overhead for functionalities outside of the scope of a specific REST API endpoint.

## Details
Currently the database has formatting and validation functionality baked into the wrapper. The code rigidly enforces that each ``Entity`` adheres to the keys defined in ``EXPECTED_KEYS_BY_ENTITY``, but there are cases for the Nimbus Validator App where an ID needs to be passed instead of automatically generated. If I were to change the code in the ``validate_and_format_entity_data()`` function, there would likely be other breaking changes.

The proposed format would allow me to edit the ``QuestionAnswerPair`` formatter in isolation in order to field this new use case.