Refactor reward/unreward Badges in backend

Created by: Tirokk

Authored by roschaefer Jul 10, 2019 Merged Jul 13, 2019

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🍰 Pullrequest

• no obsolete id
• data validations through neode
• telling error messages
• mutations return the user who was rewarded
• exclude type Badges from schema augmentation

This is a preparatory step for #277 (closed)

Issues

• None

Todo

• None