Add Python 3 suport and drop support for Python 2.5
Delay Django import until needed
Insert importer at beginning of list
Test for Python 3
Add module to sys.modules
Fix sanitizing cache key under Python 3
Don't use a raw string with \u escapes

Apparently, Python 3.2 doesn't process these in raw strings.
See https://mail.python.org/pipermail/python-list/2012-May/624756.html
and https://mail.python.org/pipermail/python-dev/2007-May/073042.html
Move force_bytes into lib module
Remove @vstoykov's note. Seems like the right place to me (:
Use force_bytes from imagekit.lib in test_cachefiles
Improve logic of contributing ImageSpecFields to Models

- If `source` is defined then register source group immediately
- If `source` is not defined then create a signal handler and attach it to
`class_prepared` signal which will see if there is only one ImageField in
the given model.

This will fix problems coused in Python 3 about using ImageSpecField
without providing a `source`.
Add Venelin Stoykov to AUTHORS
Merge branch 'python3' of https://github.com/vstoykov/django-imagekit into vstoykov-python3

* 'python3' of https://github.com/vstoykov/django-imagekit:
  Add Venelin Stoykov to AUTHORS
  Improve logic of contributing ImageSpecFields to Models
  Use force_bytes from imagekit.lib in test_cachefiles
  Remove @vstoykov's note. Seems like the right place to me (:
  Move force_bytes into lib module
  Don't use a raw string with \u escapes
  Fix sanitizing cache key under Python 3
  Add module to sys.modules
  Test for Python 3
  Insert importer at beginning of list
  Delay Django import until needed
  Add Python 3 suport and drop support for Python 2.5

Conflicts:
	imagekit/cachefiles/__init__.py