SetupHelper: Try to terminate ClassicShell Start Menu (to make upgrad…

…e a bit easier)

During upgrade from ClassicShell we'll try to terminate
ClassicStartMenu.exe as well. So that installer won't complain about files
being in use.

Add information about my clean script

Add information about my clean script

Remove AppVeyor auto build test triggering file

Remove AppVeyor auto build test triggering text file

Update README.md