Retire maven-one-plugin.

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1508648 13f79535-47bb-0310-9956-ffa450edef68
Converted to m-s-u and removed p-digester

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1508659 13f79535-47bb-0310-9956-ffa450edef68