Add "Four Styles of Object Organization" post

This post compares and contrasts four different places where you can
add related-but-not-core methods:

- Directly inside an object
- In a mix-in
- In a separate class, but delegate
- In a completely separate class

The intention is to talk about the pros and cons of each arrangement,
and be fair to both pragmatism and maintainable architecture, within
the constraints of brevity.

Change-Id: Ia8e23703196e00009f7491925d50f128cddefb20
Reviewed-on: https://gerrit.causes.com/28329
Reviewed-by: Andrew Berls <andrew.berls@causes.com>
Reviewed-by: Elliot Block <elliot.block@causes.com>
Tested-by: Elliot Block <elliot.block@causes.com>