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)
The problem is that it's quite common for me to need to build an individual project rather than doing a globalBuild. To enable that I had to repeat the function everywhere. :( Do you have a better idea? I hate approach 1 too.