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.
Some Apache license references removed
Merge pull request #34 from taigaio/license

License
Move taiga/base/auth to taiga/auth
Move contents from __init__.py to backends.py with much more docstrings.
Change auth backends authentication on common settings.