Update and clean up run_tests.sh
Update and clean up run_tests.sh

The run_tests.sh script fails when it is run multiple times on CentOS.
The `bindep` run returns an empty list of packages and then `yum`
exits with an error since no packages were provided to install.

This patch checks the length of the `bindep` output and skips the `yum`
installation when the package list is empty.

The patch also cleans up some of the old cruft left over from previous
scripts and avoids repetition.

Change-Id: I280f0a06412bc56bad87453c5aee98a626806f53
Signed-off-by: Major Hayden <18c9d4621ef6c3113ce1f960346d7603e88406e8@mhtx.net>

openstack/openstack-ansible-rsyslog_client,openstack/openstack-ansible-rsyslog_client