Revert the addition of my nickname to AUTHORS.rst, as my realname is already included

#75 already included a change to ```AUTHORS.rst```, adding my realname ("Daniel Roschka"). In 0fe93d8874317d7584fd2aacb7b0215cfe153983 you also added my nickname ("Dunedan"), resulting in two entries for me in ```AUTHORS.rst```. This commit reverts 0fe93d8874317d7584fd2aacb7b0215cfe153983 so that I only appear once in ```AUTHORS.rst```.