To do this, we need to keep integers untouched while pickling any other type
of value. Existing tests should prove that the native incr is working, but
I added a test to show that if an integer was pickled and native incr is used,
then the cache backend will convert the pickled integer correctly.

The are two reasons:
* django already implements CacheClass instance as singleton, we don't
need to reimplement that
* connection pool in redis.py is already tested, we shouldn't have to
test it again
* default keywargs charset='utf-8' and errors='strict' are defaults in
redis.py, se we don't need to copy it over

Users should handle django.core.exceptions.ImproperlyConfigured better
then a custom exception with the same name

Since redis 2.1 EXPIRE command should not return false if key exists

Django is using timeout=0 to use default timeout value.

Using timeout=0 to set non-volatile keys conflicts with django API.

Let's raise exceptions when provided bad db and port values. Also Fixed tests and bumped version.  Thanks to Lior Sion

Created connection pool that lives across requests so that we can reuse connections.  Removed close method, since we don't want to close connections at the end of a request.

We can't inherit a class from a basestring and instantiate it, so I changed
the base class to 'object' so we can still to the type checking.

I also discovered a bug with the Django 1.3 compatibility work.  In the
incr_version method, we were using the Redis's rename function to move the key,
but in Redis 2.0 you cannot rename a volitile key.

Added some moar authors

Separated the 1.3 compatible cache class from the rest of the code and reverted a few unneeded changes.

This also handles the key better internally to prevent multiple "making" of the key.

Only fall back to localhost if the URI is "redis_cache.cache://"

django-redis-cache for django 1.3 (not compatible with 1.2 : new parameters to methods in BaseCache)

Thanks to Kami for the report and Jezdez for being awesome.