Added release bundle generation script; site generation moved to a separate script; fixed script configuration phase

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/project-release-tools/trunk@1502650 13f79535-47bb-0310-9956-ffa450edef68
Added tasks to generate bin and src dist packages

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/project-release-tools/trunk@1502679 13f79535-47bb-0310-9956-ffa450edef68
Added tasks to generate MD5 digest and signatures for release dists

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/project-release-tools/trunk@1503044 13f79535-47bb-0310-9956-ffa450edef68