plexus compiler 2.3 released

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1521798 13f79535-47bb-0310-9956-ffa450edef68
remove not anymore needed snapshots repositories

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1521799 13f79535-47bb-0310-9956-ffa450edef68