Normalize build process with other OIE plug-ins

[ChristopherSchultz]

The build process currently requires some ugly hacks like

1. Manually downloading and installing mirth core libraries into libs/
2. Generating a signing key and certificate, then using it
3. Using the bundle.sh script to put all the pieces together

It would be nice if there was a more straightforward build process.

This build also uses Maven, which doesn't appear to be the build-tool of choice for the parent project.