[App] Teacher roll call

[danlg]

Implement in the app for teacher the ability to do roll call.
This page is available only for teacher:

• Page 1. Select class that you want to do roll call with class avatar
• Page 2 for this class displays all students (filter out other user is there are parents for instance)
  and list then

Student 1 o
Student 2 o

When clicking on the radio button, it replaces with a tick, when clicking a again, it replaces with a cross (missing), when clicking again it puts as present (tick again). Each time there is a click it send a real time event to the server (time out of 3 sec to send event if present to avoid sending present and then absent again).