Qpid, RabbitMQ: advance thru the list of brokers on reconnect

When using multiple brokers, we don't want to immediately retry failed
connection for the same failed broker. This was not the case in
existing implementation though, where we've always attempted to
reconnect starting from the first broker in the list of candidates. So
if the first broker failed, we initiated reconnect to the same failed
broker.

This change makes reconnect() implementation to select the next broker
in the list. This also means that non-failure reconnect attempts will
also switch the current broker. All in all, users should not rely on
any particular order to use brokers from the list, so this should not
constitute an issue.

This sync includes the following fixes for HA deployments:
* Ia148baa6e1ec632789ac3621c85173c2c16f3918
* I67923cb024bbd143edc8edccf35b9b400df31eb3

Change-Id: I77be95dd2db4546297d597032055459a12b52cfa
Closes-Bug: 1261631
Merge "Qpid, RabbitMQ: advance thru the list of brokers on reconnect" into stable/havana