[models] do not include models with the code

[JulienPeloton]

The models are getting too big! We can keep them inside the repo, but they should not be distributed via pypi (limit of 100MB already reached).

Strategy 1

• each processor should have an argument to get the path
• models should be copied to this location

This has the advantage to keep pypi to distribute the code, but there is an extra burden to synchronize with the models...

Strategy # 2

Alternatively, we can stop using pypi for this repo, and install using the URL directly (using releases):

pip install git+https://github.com/astrolabsoftware/fink-science@RELEASE

Of course, we will hit some limit later (about 5GB). I personally prefer this one though...