Fix society filter in member achievements

Ghost User
2019-08-14T09:48:21+02:00

Closes #899

#### Previous behaviour
1. Go to [Joren's profile page](https://thalia.nu/members/profile/1239).
1. Notice that "Cooks' Guild" is listed under "ACHIEVEMENTS FOR THALIA" and "SOCIETIES".

### Expected behaviour

1. Go to [Joren's profile page](https://thalia.nu/members/profile/1239).
1. Notice that "Cooks' Guild" is listed under "SOCIETIES" only.