add gitignore to ignore files by git

git-svn-id: https://svn.apache.org/repos/asf/james/hupa/trunk@1522324 13f79535-47bb-0310-9956-ffa450edef68
update git ignore

git-svn-id: https://svn.apache.org/repos/asf/james/hupa/trunk@1522325 13f79535-47bb-0310-9956-ffa450edef68