[maven-release-plugin] prepare release maven-assembly-plugin-2.5.1

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1635543 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1635545 13f79535-47bb-0310-9956-ffa450edef68