Sometimes messages to Zaqar fail with with the following error.
> Error response from Zaqar. Code: 503. Title: Service temporarily
> unavailable. Description: Messages could not be enqueued. Please
> try again in a few seconds..
When this happens we should retry as it states. This change has
the task retry calling the queue_post action a maximum of 5 times
with a 1 second delay between each attempt.
Closes-Bug: #1626103
Change-Id: Iba272004a8adb7ebc5122fc47764dbf81925bc62
Dougal Matthews
7ee66120ac