Implement a HexIntegerField solution to store GCM device_id with.

Fixes #1
Mention Python 3 support in the docs
Merge branch 'hex-udids'

Conflicts:
	push_notifications/models.py
Add introspection rules for HexIntegerField
Add south migrations for hex-udids
Fix HexIntegerField.db_type() super() call
Treat empty strings as None in HexIntegerField
Release 0.9.90
Add travis-ci build image
use '==' for comparison against empty string instead of 'is'
Merge pull request #20 from marconi/master

use '==' for comparison against empty string instead of 'is'
Add additional exceptions for flake8
Drop an unused import
Final flake8 fixes
Due to django.utils.six being required, do not run tests on Django 1.3 and 1.4
Fallback to systemwide six on older versions of Django
Document six requirement on <1.5
Remove get_internal_type and let the parent class handle it.
Merge pull request #19 from emperorcezar/master

Use bigint for db_type
Add an AUTHORS file