Adding Banno/jsonz to community build.

We also have a couple of sbt plugins that we can offer up as testable.

* https://github.com/Banno/sbt-license-plugin
* https://github.com/Banno/banno-sbt-plugin

Would there be interest in using those? (Both have a couple of tests.) I don't really see any other sbt plugins here under test.
Whoops, fixed that.