Eliminate feature.yangtools.version
Eliminate feature.yangtools.version

This property is not used anywhere, remote it.

Change-Id: Id96e61006cf06ac5c1dc0c99ab24f581db30ab0e
Signed-off-by: Robert Varga <91ae5aa8c7a9f7e57b701db766e23e544aaa6ae9@pantheon.tech>

opendaylight/dlux,opendaylight/dlux,opendaylight/dlux