config/v2_0: changes to fallback to v1 parsing and translate on error
config/v2_0: changes to fallback to v1 parsing and translate on error

When an error parsing (or too old) config is encountered, attempt to use
the v1 parse function and translate the result to 2.0.0.

coreos/ignition,ajeddeloh/ignition,coreos/ignition,ajeddeloh/ignition,coreos/ignition,ajeddeloh/ignition