QPID-5097: Create a Dispatch source tarball.

Created a script that will check out the subversion repository at a
specific branch and revision, and then create a tarball of just the
Dispatch sources.

Also added standard files [ChangeLog, LICENSE, TODO] that should be a
part of the sources as well.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1517825 13f79535-47bb-0310-9956-ffa450edef68