Blender Git Loki

PyTests: do not load addons in load_py_modules test.

It makes no sense to load add-ons here, we already do that (in a more
complete way) in load_addons test, this is only adding overhead and
doubling code to maintain).

Also do not try to load-as-modules add-ons that are not 2.8-ready, and
some other misc fix.

load_py_modules test should be passing again now.

Thanks to @sergey who did part of the work here as well.