Nova has deprecated the server-side keypair generation process, which
is used by cinder's resource create phase in grenade. Even though it
still works for old microversions, it generates RSA keys which will
not be accepted (by default) in newer distros. This makes us generate
the keypair locally and upgrade the public key instead of generating
it server-side.
Change-Id: I0275a44f2ec4977b085b8129fd06e80a0ed6e68d
8fdda79453