Added closing of zip file to avoid VM going into hindenburg mode

Zip files are dangerous things

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1626500 13f79535-47bb-0310-9956-ffa450edef68
Close some more ZipFiles.

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1626501 13f79535-47bb-0310-9956-ffa450edef68