Make redis.lrange('foo') return the entire list

Redis does not have a no argument command to retrieve the entire list.
Instead of remembering to run:

  r.lrange('foo', 0, -1)

default start to 0 and end to -1 making it possible to just run:

  r.lrange('foo')

If only start is specified, behavior remains sensible (all list elements
from that index onward are returned).