[MSOURCES-83] Make Plugin only Maven 3.0 minimum - Lifted Java limit to 1.6 in accordance with 3.0.0 - Replaced maven-project dependency with dependency to maven-core. - Upgraded maven-plugin-testing-harness to 2.1 which   needs maven-compat to work which is only in scope test.
[MSOURCES-83] Make Plugin only Maven 3.0 minimum
- Lifted Java limit to 1.6 in accordance with 3.0.0
- Replaced maven-project dependency with dependency to maven-core.
- Upgraded maven-plugin-testing-harness to 2.1 which
  needs maven-compat to work which is only in scope test.


git-svn-id: 6038db50b076e48c7926ed71fd94f8e91be2fbc9@1705678 13f79535-47bb-0310-9956-ffa450edef68

rkorpachyov/maven-plugins,lennartj/maven-plugins,apache/maven-plugins,zigarn/maven-plugins,krosenvold/maven-plugins,mcculls/maven-plugins,lennartj/maven-plugins,hazendaz/maven-plugins,mcculls/maven-plugins,apache/maven-plugins,hgschmie/apache-maven-plugins,mcculls/maven-plugins,rkorpachyov/maven-plugins,hgschmie/apache-maven-plugins,restlet/maven-plugins,HubSpot/maven-plugins,hazendaz/maven-plugins,HubSpot/maven-plugins,HubSpot/maven-plugins,restlet/maven-plugins,rkorpachyov/maven-plugins,restlet/maven-plugins,krosenvold/maven-plugins,hgschmie/apache-maven-plugins,krosenvold/maven-plugins,restlet/maven-plugins,mcculls/maven-plugins,zigarn/maven-plugins,rkorpachyov/maven-plugins,apache/maven-plugins,hazendaz/maven-plugins,zigarn/maven-plugins,apache/maven-plugins,apache/maven-plugins,sonatype/maven-plugins,HubSpot/maven-plugins,sonatype/maven-plugins,rkorpachyov/maven-plugins,sonatype/maven-plugins,hgschmie/apache-maven-plugins,zigarn/maven-plugins,lennartj/maven-plugins,hazendaz/maven-plugins,sonatype/maven-plugins,hazendaz/maven-plugins,krosenvold/maven-plugins,lennartj/maven-plugins