Remove explicit dependency on amqplib

kombu already depends on amqp or amqplib depending on its
version, and no explicit access to amqplib exists in neutron code.

Closes-Bug: #1317094
Change-Id: I5cf189d7173b732cba6df3f9b6aff1d2bb85cdfe
Start ping listener also for postgresql

Make use of the automatic connection disposal for
PostgreSQL as well.

oslo-incubator commit: 4a591eaafe035fa3fd508c910f057bfa8ff51005

Change-Id: I6e6adb612968639dbc8deae31e5409aac44e340e
Closes-Bug: 1288438
Merge "Start ping listener also for postgresql"
Merge "Remove explicit dependency on amqplib"