Alcherializer

Feature
- Serializer accepts `context` kwarg which receives a dictionary of things to be passed down to other serializers also

Chore
- Adds `.pytest_cache` to gitignore
- Creates a docker container to be used as dev environment
- Create contribution guidelines

Feature
- Parse enum.Enum classes values when serializing 2

Feature
- Serialize related models
- `alcherializer.fields.MethodField` allowing add custom fields to serializer

Style
- Refator code with black, flake8 and isort

Tests
- Refactor tests with pytest

Docs
- how to use related fields
- how to use `alcherializer.fields.MethodField`

Feature
- alcherializer.fields.MethodField

Feature
- Serialize related models

Tests
- Refactor tests to work with pytest

Style
- Using black, flake8 and isort to guard code style