- Got rid of _prepare_key and _prepare_value
- Started using the base64 module directly
- Use the highest pickle protocol available
- Added a set_many method
- Added a delete_many method
- Added an expire method
- Made get_many return a dictionary as required

Got rid of the incr and decr implementation since we can't really increment/decrement the base64'd values.

Fixed a default timeout problem - if no timeout was specified the default timeout specified in settings was not used.

Now, you have three choices:
1. no timeout is specified - the default timeout is used
2. timeout is specified and it's not False - the specified value is used
3. timeout is specified as False - no timeout is set for this key and it does not expire

encode/decode base64 - you can't throw direct pickles at redis-py, because it tries to treat them like unicode.

Client libraries are no longer included with redis, so updated README to point to the redis client library