Added ability to configure the Redis connection.

 * Redis setter code shamefully borrowed from the Split gem.
   https://github.com/andrew/split/blob/master/lib/split.rb#L32
 * Added Redis configuration docs to the read me.
 * Added Redis::Namespace and a default forgetsy namespace.
Merge pull request #1 from LessonPlanet/redis-configuration

Added ability to configure the Redis connection.