add credits in group model and consume from there

[vinibgoulart]

• [ ] add field credits
• [ ] consume credits when receive some message
• [ ] min: 5 points (all messages)
• [ ] gpt - 8 points
• [ ] resume - 10 points
• [ ] middleware with validation
• [ ] ignore defaultMessage, !init, !resume-start and !resume-stop

[samueldurantes]

I can grab this one, what is the points default that a group starts?

[vinibgoulart]

start with 200 credits