X509 certificates are used by Windows for passwordless
authentication (WinRM) in a way which can be considered
consistent with the usage of SSH keys on Linux, as both
are based on public / private keypairs.
Adds 'type' field to the keypair object and database tables.
Adds necessary database migration to add keypair type to the
database tables.
This commit is necessary in order to have different types
of keypairs (e.g. ssh keypair, x509 keypair)
Partially implements: blueprint keypair-x509-certificates
Change-Id: Iae18687e2ceabb22d790d5abd872d773265abcbe
b4d57ab658