Partial update method now is also transactional as its friend update method.
Add own subclass of generic view set.
Add new NotSupported exception.
Micro refactor on domain api viewsets.
Cosmetic changes on taiga.routers module.
Cosmetic changes on taiga/routers.py
Convert bulk update services classes to simple functions.

Because we are using python and not java ;)
Move videoconference choices from project models to choices modules.
Cosmetic fixes on choices and models of projects app.
Unify aggregates and project services.
Replace main license file.
Replace license on taiga.domains module.
Replace license on taiga.events module.
Replace license on taiga.projects.aggregates module.
Replace license on taiga.projects.tasks module.
Replace license on taiga.projecrs.issues module.
Replace license on taiga.projects.userstories module.
Replace license on taiga.projects.wiki module.
Replace license on taiga.projects module.
Replace license on taiga main module.