MB-100: import socket missed in task.py

Change-Id: Iee4d83f3b25e4136d133f9f840f88f030bbc7a9a
Reviewed-on: http://review.couchbase.org/24699
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>