Implement main web page

[kolnol]

• [ ] (Optional) Check what is Ajax to implement communication with the server.

• [x] After logging in, the interface should check in the background whether the student is already registered in a group. (You can request the current user object from the server and check if he has a group.)

If the student is not registered in any group:

• [x] The web-app interface should show a list of available groups. The student must choose a group from the list in order to register himself/herself.

If the student is already registered in a group the web-app interface should show:

• [x] The number of the group

• [x] The time and place of the weekly exercises for that group

• [x] The name of the instructor

[PhuongMaiMai]

Suggestion for group list view: Introduce similar fields like on TUM Online and add the following

• Registration from/to
• Sign out from/to
• Number of participants max/is/WL
• (Registration method(FCFS))
• date, start and end time

[PhuongMaiMai]

Status

• Currently, log in with any data as long as it is not empty.
• A registered student can also see the list of groups in order to hold a "Move tutorial group" feature open in the future.
• The web app shows the view of a registered student

Additional

• list is extended according to the last comment
• Homepage is added

[PhuongMaiMai]

• [x] adapt code: currentNrOfParticipants is not in server response
• [x] attend button with generating qr code in home page

[georgiayloff]

Well done, @PhuongMaiMai! Keep it up :)