Updated contributing guidelines.
Updated contributing guidelines.

Specifically, added help for getting started, and removed coding style which
is a bit overkill for a project this size - PEP8 is enough.

chriscauley/django-mailer,ryanshawty/django-mailer,Ubiwhere/django-mailer,jawed123/django-mailer,pinax/django-mailer,pinax/django-mailer,temnoregg/django-mailer,felixxm/django-mailer,spookylukey/django-mailer