Fix build problems caused by our old Java version

Created by: yngwi

Fixes issue #735 (closed) by removing the download of tools during the build process and instead adding the used tools as zip files to the vendor directory. This has the disadvantage that the repository will get significantly bigger (eXist has ~60MB and betterFORM has ~130MB file size) but on the plus-side, our build can not be broken by outside changes (happened several times already) and the tools don't have to be downloaded anew each build, so the build process is faster depending on the building machines' internet connection.

I'm not so sure whether or not to use this fix also for the upcoming eXist-3 based version as we don't have this problem there and we would like to stay up to date with the tools that are still not abandoned (I think the last betterFORM version is from 2014).