Bump maven-dependency-plugin version

mvn dependency:tree fails with the old version (2.6) due to classpath
inconsistencies. With this bump, it succeeds.

Change-Id: I8054a1c97158f5bbf43fa41b410d8245a5ae95a4
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "Bump maven-dependency-plugin version"