JAVA_HOME error on computer without Java

[vanmeerkerk]

A fresh install of the venv and running app.py results in a error. The PC does not have a Java installed and so JAVA_HOME is not findable.

[MichielTukker]

To resolve this, we need to refactor the ates class and mappers. Ates imports pyjnius at the root of the file, mappers import ates a the root, so as soon as the mappers are loaded/called, it crashes because java is not installed.

[MichielTukker]

Closed by #216. Because Pyjinius is only loaded when the Ates class is initialized, pyjjnius does not have to be installed (unless you want to run a model with an Ates)