MB-7832: Use PumpQueue instead of Queue

System shipped Queue has less support for python 2.4.3

Change-Id: I37f424c2e36f4e80187972afe7f758b4f5e7d6ad
Reviewed-on: http://review.couchbase.org/24900
Tested-by: buildbot <build@couchbase.com>
Tested-by: Bin Cui <bin.cui@gmail.com>
Reviewed-by: Steve Yen <steve.yen@gmail.com>