[MPLUGIN-278] updated Maven prerequisite to 2.2.1 (parent pom was already updated, but not the plugin...)

git-svn-id: https://svn.apache.org/repos/asf/maven/plugin-tools/trunk@1637736 13f79535-47bb-0310-9956-ffa450edef68
avoid 'Default target for maven-compiler-plugin version 3.1' info in plugin-report

git-svn-id: https://svn.apache.org/repos/asf/maven/plugin-tools/trunk@1637746 13f79535-47bb-0310-9956-ffa450edef68
code simplification

git-svn-id: https://svn.apache.org/repos/asf/maven/plugin-tools/trunk@1637747 13f79535-47bb-0310-9956-ffa450edef68