Add factories to all djangoldp package

Maybe this issue is not on the right repository, feel free to move it.

In order to implement automatic tests (1) - and speed up installation for devs (2) - I propose to add factory to all django ldp package.

Example :

In my test runner, I call a commandline to add some fake data for a model. I shall see the generated data in the DOM
In my test runner, I add some data on two different server. I shall see both in the DOM

Currently, on a fresh server installation, there is no data. So, I need to add manually some data to test. At every change on django ldp package, I shall repopulate the server and lose time to do it.

I found this package (https://factoryboy.readthedocs.io/en/latest/orms.html), maybe there is other to do the job.