Replace Karma system with Thanks System

[andy3471]

Is your feature request related to a problem? Please describe.
Users can add fake steam games to increase karma, so we are currently incentivising spamming false keys.

Describe the solution you'd like

• Remove karma incriment in adding a key
• Remove karma decriment when claiming a key
• Add migration to add thanks to keys (possibly with a message)
• Add a "Send thanks" button on a key view, after claimed
• Controller to add thanks, which incriments karma for the person that donated the key.
• Replace current karma calculation command to count the amount of thanks you have
• Replace Karma calculation in user model with new system