The selected key type is defined by kubeadm's --feature-gates option:
if it contains PublicKeysECDSA=true then ECDSA keys will be generated
and used.
By default RSA keys are used still.
Signed-off-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>
Replaced hardcoded "v0.12.0" strings with MinimumControlPlaneVersion and
MinimumKubeletVersion global variables.
This should help with a regular release version bumps.
