use ${pom.groupId} instead of hard coding maven.

git-svn-id: https://svn.apache.org/repos/asf/maven/maven-1/plugins/trunk@114152 13f79535-47bb-0310-9956-ffa450edef68

plugin/plugin.jelly

@@ -14,7 +14,7 @@
     <attainGoal name="jar:jar"/>
 
     <copy file="${maven.build.dir}/${maven.final.name}.jar"
-      todir="${maven.repo.local}/maven/plugins" />
+      todir="${maven.repo.local}/${pom.groupId}/plugins" />
 
   </goal>