add --distribution patch (Closes: #819537)

Author: Martin Gerhard Loschwitz <m.loschwitz@syseleven.de>
Date:   Wed Mar 30 10:18:20 2016 +0200

Add the "--distribution" parameter

This commit adds the "--distribution" paramater, effectively allowing to
specify the target distribution in the changelog of the resulting java
package. This feature is particularly helpful when dealing with local
repositories maintained by software such as reprepro and organized based
on different distributions.