Achievement meta information

[frederike-ramin]

Achievements should have meta information like name that can be used in the frontend.

[cmfcmf]

The idea here is to introduce a new meta: key in the achievement configuration which can contain any kind of information, depending on the use case. You could, for example, set meta: {title: 'blah', desc: 'queue', color: "#974562"} for one achievement and use these values in the frontend. The achievement's meta-data should also be included in the /user/<user id> responses for all granted achievements.