[#123] Add Contibutor listing

Created by: elbenfreund

This PR adds a listing of all contributors so far. Future contributors should add themselfs here, which should be pointed out in the contribution guidelines.

We separated contributors up to today as 'original authors/contributors' in order to provide a clear cut for any potential upcoming refactoring that may be required and to be as transparent as possible.

Closes: #123 (closed)