add gmaven-plugin example in pom

git-svn-id: https://svn/IT/az/groovy@23794 99cadc30-3bf9-11df-9bc1-510916f65ae8
add antrun-driven local repository cleaning

git-svn-id: https://svn/IT/az/groovy@23797 99cadc30-3bf9-11df-9bc1-510916f65ae8
use more fancy <delete> task

git-svn-id: https://svn/IT/az/groovy@23817 99cadc30-3bf9-11df-9bc1-510916f65ae8
Merge remote-tracking branch 'remotes/git-svn'