Miscelanous fix for Eclipse users

- Make sure the jacoco-maven-plugin is not contemplated by m2e in md-sal.
- Make sure the assembly target runs from the release pom project as
opposed to the distribution as it was done before.
- Silent warning from the module
org.opendaylight.yangtools.yang.parser.util.ModuleDependencySort they
don't seem at all warning rather simple advices

Change-Id: I379274caff84c29c1f815c14b1d8530ac689957d
Signed-off-by: Giovanni Meo <gmeo@cisco.com>