Keycloak backend Connection

[Mohido]

For this PR, I setup a new Keycloak realm for our project and created a new client (Application entry point) and 2 users (teacher-1 and student-1) with 2 different roles (demonstrator and student). Moreover, I added basic test endpoints to the backend to test the functionalities of the 'keycloak-connect' package that we are using. You can test the connection in various of ways:

• You can check if keycloak is setup correctly by starting the project and going to any of the containers (docker exec -it <container_name> sh) and execute the following shell script: wget -O - --header 'Content-Type: application/x-www-form-urlencoded' --post-data "username=teacher-1&password=123&client_id=cap-app&client_secret=aQX4Vdbe7PhQTPCwRdeOwIdQzbpGkOdw&grant_type=password" "http://nginx/auth/realms/CAP/protocol/openid-connect/token". The previous script will give you an access_token if the connection was established. For now I typed the user credentials manually for testing.
• You can start the whole project and wait until everything is fired up (Specially keycloak). Then open your terminal if you are on linux and type: wget -O - "localhost:5000/gettoken". The previous command will activate an api endpoint that will try to login to the client (cap-app) as "student-1". The request will return 200 which means that it was successful. To see the output and make sure it works, write the following command docker-compose -f docker-compose-local.yml logs -f backend. It will printout the backend logs and will keep watching the logs for changes (coz of the second -f flag).

I edited also the auth_db and imported the newest Keycloak database. The new database contains the stuff mentioned in the first sentence of this description.

[Mohido]

@Abdulla-Alkhulaqui @the4t4 @RealGorandos A call for review and comments!

[the4t4]

@Mohido added some comments and some questions

[Mohido]

@the4t4 Changed the stuff. Have another look and if you are fine with it then we can merge