Allow configurable version numbers for binaries

* Use system properties to set version number, maven remote repo, maven
credentials
* Remove gradle.properties as gradle prioritizes those system properties over those supplied over the command line (which is stupid)
Sigh.... I do like getting rid of the function. I just didn't want people having to manually type paths in their config file. It's one of those things that breaks really easily. But oh well, let's go for it. Nuke the function. Just please make the other changes and re-submit. Same for the other PRs.