Composite droplets support

This release introduces quite handy feature for tasks which make you attach multiple droplets at the same time to achieve single side effect. For example a set of droplets for preventing an application from communicating with outer world through various channels.
Usually you have to attach each droplet separately but from this version on you can put them all into single ZIP (or JAR) archive and attach it to jMint just like ordinary droplet. Such archive is called composite droplet. jMint recognizes composite droplets by their extensions (.zip or .jar) and opens them for processing. It then traverses archive fully and ignores everything except files with .java extension (droplet itself). Such behavior allows you not to bother about directory structure inside the archive as well as let you put some additional files into archive, for example readme.txt.
All the droplets extracted from composite droplet are included into targets map in the same way as ordinary (separate) droplets.