rbdmap.service should include RBDMAPFILE environment variable
/usr/bin/rbdmap requires the RBDMAPFILE variable to be set. I've worked around this on my machines by adding Environment=RBDMAPFILE=/etc/ceph/rbdmap to the systemd unit file.
qa: test_rbdmap_RBDMAPFILE.sh workunit
Before a7a3658 the rbdmap script was logging bogus messages and not working
on systemd platforms because the unit file was not defining the RBDMAPFILE
This workunit asserts that the bug has been fixed.
Signed-off-by: Nathan Cutler <email@example.com>