[maven-release-plugin] prepare for next development iteration

Change-Id: I7a8f8b78699adaa8db9a370517d7901dda9caeaa
Fix Nexus integration after Sonatype changed public API (again) in 2.6.

Note - the extra parameter is ignored in older Nexus versions.
The status URL no lomnger returns client permissions by default - so explicitly request them.
[maven-release-plugin] prepare release m2release-0.12.0

Change-Id: I395255dca8c4beabf6554391d96d2f67e1bb1257
[FIXED JENKINS-15983] added possibility to define a custom SCM tag template