Update ensure()/reconnect() to catch MessagingError

The error handling code that gets connections reset if necessary
caught ConnectionError. It really needs to catch MessagingError,
which ConnectionError inherits from. There are other types of
MessagingErrors that may occur, such as InternalError, and they need
to cause the connection to reset, as well.

This fix has already been merged into oslo.messaging.
https://bugs.launchpad.net/oslo.messaging/+bug/1303890

Change-Id: I121aaf87dfaec978d6313d095f5cf99ad8e3cec4
Resolves: rhbz#1086001
Reviewed-on: https://code.engineering.redhat.com/gerrit/29330
Tested-by: RHOS Jenkins <apevec+rhosci@redhat.com>
Reviewed-by: Zane Bitter <zbitter@redhat.com>