Add connection_pool to redis-objects

I added a connection-pool object into redis-objects, the change is not backward-compatible, so I don't expect you to accept directly the pull request.

Also I could not make the following tests to pass:
  - should support interpolation of key names [FAILED]
  - should raise an exception if the timeout is exceeded [FAILED]

Do you have any suggestion on how to ask the community to support this change?

Tnx, @felipeclopes