add Sebastian Fricke to the contributer list

contributors.md

@@ -128,3 +128,4 @@ Thank you to all contributors:
 * [Stefan20162016](https://github.com/stefan20162016)
 * [Marco Torsello](https://github.com/md1512)
 * [Bruno Meneguele](https://github.com/bmeneguele)
+* [Sebastian Fricke](https://github.com/initBasti)