Refactor views to viewsets

Closes #58.

See merge request !17

* IT waS A FUCKIng tyPO
* ran isort and flake8 and fixed reported issues

Merge branch 'refactor-views-to-viewsets' of gitlab.gwdg.de:j.michal/grady into refactor-views-to-viewsets

Currently students and tutors have access to the /tutor/ endpoint in the browsable api and at least get a 200 response in the tests for the /student/ endpoint however can not access this one in the browsable api.

* no url configuration needed simply register viewset with router
* now using DefaultRouter, meaning api root is now browsable
* merged some views
* makes it easier to include api schema later
* Ran isort and updated docstring

Backend tests

Closes #50

See merge request !16

* Also added docstrings to classes and module in views.py
* Removed a logging statement from StudentApiView

- changed unittester from ./manage.py test to pytest in CI
- implemented tests for various views see previous commits
- coverage should now produce html output for test coverage

* ran isort on all test files

allowed to fail

* also moved test concerning access rights to another test suite

This reverts commit 0acfd677.

The methods in core.tests.data_factories.py are not finished nor good and overlap with GradyUserFactory.

Also set TEST_REQUEST_DEFAULT_FORMAT to json in default.py

Refactor

This should be the final commit before actual work can begin. See the corresponding issues for more information on what this branch is about.

A few highlights include:

* A working vue.js project
* CI/CD has been set up
* All now dead code in the packend has been cleaned up
* The structure of the repository has been renewed


Closes #47, #41, and #40.

See merge request !15

Pre commit

See merge request !14

To enable the pre-commit checks first run pip -Ur requierements.txt to install pre-commit. Next run pre-commit install to install the hook in your .git/hooks folder. Running pre-commit will now run prospector on all new or modified files in the backend/ directory (see pre-commit-scripts/prospector.sh for the arguments that are used). If you get an error saying prospector not found or smth. make sure you have the venvv activated or prospector installed globally.

Not working!

- the forntend will now be part of the main image since its static
anyway
- The frontend has a testing stage
- reorganized .gitignore files
- docker-compose works as expected
 - serving api on 8000
 - serving frontend on 8080