Applying the new novoda bintray release plugin

Removes the maven and signing plugins in favour of the new novoda release plugin.

- We lose the ability to release snapshots but we've agreed that we will no longer be using them.
yes you can do `publishToMavenLocal` and that'll generate them in your local maven repo. And I'm not 100% sure but I think you can also do `uploadArchives` to generate the jars in the `build/release` dir of the project