testnode: Add support for OpenSUSE Leap 15.0

testnode: Add support for OpenSUSE Leap 15.0

Some notes:

  - Setting hostname with ansible fails.  It's a known issue.  Bug is in
the yaml.  teuthology sets the hostname after FOG provisioning anyway so
NBD.
  - Leap mounts all of the root subdirs as separate mountpoints so the `zap`
tasks had to be modified to not wipe those out
  - The sshd config is named `sshd_config_opensuse_leap_NA` because the
task that installs the SSHD config uses {{
ansible_distribution_major_version }} which isn't set to 15.0 in Leap
apparently.

Signed-off-by: David Galloway <dgallowa@redhat.com>