Load JAR files dynamically at Runtime

[luigi-asprino]

This could be useful for adding custom triplifiers or functions without having to recompile the whole project.

I found this

https://stackoverflow.com/questions/60764/how-to-load-jar-files-dynamically-at-runtime

If there aren't better solutions, we could add a CLI option for passing the filepaths to the jars to be loaded.

[enridaga]

This is also related to the problem with packing a very large executable jar, even if not all the features are always needed. This was discussed in #484 but we didn't come out with a plan yet.