Fix applet setup

**Disclaimer** The applet fires up, but does not work properly yet.

Changes:
* The root folder is clean now, the libs folder contains only relevant libraries and the latest engine jar.
* Modules can be specified on the command line and are stored in the mods folder
* During startup the applet download the module jar and puts them locally into "modules"
* Added logging config (as in the PC facade)
* Jars are signed in parallel which is a lot (5x-10x) faster than before

Open issues:
* Natives are not extracted. I think this is indicated by the "Certificate mismatch found" error message. The cause could be that vecmath is signed with a different certificate. Re-signing is not possible out-of-the-box, because the original SHA values are still stored in the MANIFEST file. Workaround: copy the files manually
* Weird (race condition?) error when signing jars in parallel: "manifest doesn't support the nested "signjar" element" (line 169) - probably easy to fix, but I don't know how to ..
* Modules are discovered and listed in the "Create Game" dialog, but no content is available. ReflectionUtils throws an exception searching through the Core module - maybe this is security-related, but I can't see how. Maybe also related to https://github.com/MovingBlocks/Terasology/issues/1067