Add support for Django 1.6 and Specifying secret_key via Constructor Argument

This release adds support for Django 1.6 by attempting to import from external localflavor (django-localflavor) before falling back to the included version for Django 1.5.x and earlier. It also allows you to specify a secret_key value during field instantiation, rather than using the default value from django.conf.settings.

v0.2.2: Merge pull request #35 from bltravis/master

This release fixes some issue introduced v0.2.1. See README.md for details.