BUG-1402: removed hardcoded plugin version for testing.

In test-parent/pom.xml was hardcoded yang-maven-plugin version in property it-project.version.
This patch remove this property and use parent pom version.

Change-Id: Ib6478c839abcc54a0862439b201b4889f2af5cc7
Signed-off-by: Martin Vitez <mvitez@cisco.com>
Merge "BUG-1402: removed hardcoded plugin version for testing."