Call API to send bonuses

[Ovifer13]

Issue #829

• Call API when sending bonuses
• Handle successful and failed payments

Proof

[otech47]

refactor ContributorInput in the PaymentType schema to disambiguate it

i suggest

input ContributorBonus {
  contributor_id: Int!,
  amount_to_pay: Int!,
}

[otech47]

For the sendPayment function, the contributors could be more explicit as contributorsToPay