At the moment we do generate SSH keypairs for octavia with pre-defined
options for backwards compatability.
In the meanwhile it might not make much sense for new deployments,
though there's no clear way to overrride these options.]
With that we implement a bunch of new variables that allows to tune
properties for the SSH key to be used.
Change-Id: I5c4c20e7375b2471cc47ac628e007d6297bdeb7e
(cherry picked from commit f976e5fd281f28fecb4e5f7d2be3e8c9769adceb)
b29b7a6f3c