Add long-polling support to SQS transport

The polling interval was set to 0 and a new
transport option (wait_time_seconds) was added.  This
parameter specifies how long to wait for a message from
SQS, and defaults to 20 seconds, which is the maximum
value currently allowed by SQS.

Fixes #176.  Closes #198.
Adds James Saryerwinnie to AUTHORS
Minor typo fix in "fake" imports for static analyzers.
Adds Basil Mironenko to AUTHORS
Merge branch '2.5' of https://github.com/celery/kombu into 2.5