[Feature] - Custom Captchas

[Paulsenik]

Is your feature request related to a problem? Please describe.
PRoST-Users sometimes are too drunk to be responsible to drink more.

Describe the solution you'd like
The UI should randomly prompt custom captchas to the users before confirming a transaction. These Captchas or little "games" try to find out if the user is sober enough to buy again.

• The user on this device won't be able to buy after 1-3 failed attempts.
• Games
  • Find the drunken Student
  • Type the first 10 decimaldigits of pi
  • Solve a git-problem and type the correct git-command.
• Browser- and Clientside Sessionlogging and device-detection should be used to prevent cheating 🙃