Turned Tkinter GUI into webapp

[Genius-Raptor]

Hello, I noticed that there was an open issue (#72) saying that the tkinter GUI should be converted into a flask webapp. So I reconstructed the GUI in HTML and used bootstrap to beautify it a bit which should solve #101. If you find any problems with the PR, you can ask me to fix it, but since I am not online all the time, you can change it as you see fit.