remove all useless header comments (#3363)

see #3358

used command: `find ./ -type f -exec perl -i -0pe
's/\/\*\s*magicmirror.*?\*\/\s*//si' {} \;`

This is a first draft, I think we should preserve some of the comments.

tests/configs/modules/positions.js

@@ -1,8 +1,3 @@
-/* MagicMirror² Test config for position setters module using the helloworld module
- *
- * By Rodrigo Ramírez Norambuena https://rodrigoramirez.com
- * MIT Licensed.
- */
 let config = {
 	modules:
 		// Using exotic content. This is why don't accept go to JSON configuration file