File generation cleaned

See merge request chehabfl/outgoing_rex!26

Centralized viewset permissions, added obj_moderation_level [not tested], cleaning

See merge request chehabfl/outgoing_rex!25

Better api integration

See merge request chehabfl/outgoing_rex!24

Currency update

See merge request chehabfl/outgoing_rex!23

Backend simplification

See merge request chehabfl/outgoing_rex!22

usefull links validation using custom validation

Add new unit test that make it fail

Better backend generation (now with admin.py)