openstack-ansible-rabbitmq_server/tests at b42372bbc9e6b7cb5700efa498d05ee67d3b2416 - openstack-ansible-rabbitmq_server - OpenDev: Free Software Needs Free Tools

Change the default install version of RabbitMQ Server to 3.6.3.
The 3.6.3 Debian package adds support for systemd and no longer leaves a
rabbitmq-server process running for signal handling to the erlang VM.
The `pgrep` command checking that rabbitmq is running has been updated
to search entire process names to account for this change.
Change-Id: I742b03f64cd0232835b7143507e3d3cd14d79f23