Use config options to determine message count
Use config options to determine message count

This patch replaces the hard coded message count with a parameter
that is read from the config file. This is needed to run the functional
tests against vendor specific implementations of Marconi.

Change-Id: I188463749630b051174eed44bacb2b6d52c8c82d

openstack/zaqar,openstack/zaqar,openstack/zaqar,openstack/zaqar,rackerlabs/marconi