BUG-868: move to use unified ClassLoaderUtils

This is a follow-up for yangtools patch
https://git.opendaylight.org/gerrit/#/c/7160/ . It updates the imports
to use the newly exposed version of ClassLoaderUtils.

Change-Id: I7178475ae698c3ba7120cf5ddfe56c4094f23d8b
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-868: move to use unified ClassLoaderUtils"