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.

modules/default/clock/clock.js

@@ -1,11 +1,5 @@
 /* global SunCalc, formatTime */
 
-/* MagicMirror²
- * Module: Clock
- *
- * By Michael Teeuw https://michaelteeuw.nl
- * MIT Licensed.
- */
 Module.register("clock", {
 	// Module config defaults.
 	defaults: {