Integrate Coinbase Payments

Frontend
- add new button called ‘deposit’
- user clicks button and enters amount $
- get users blockchain address from firebase
- Create-a-charge API request it sent https://commerce.coinbase.com/docs/api/#create-a-charge
- redirect user to ‘hosted url’ in api response
- backend waits for confirmation from webhook
- send tokens to user
- add API response to firebase new database deposit

Backend
API documentation: https://commerce.coinbase.com/docs/api/#introduction
NodeJS backend code: https://github.com/coinbase/coinbase-commerce-node/blob/master/examples/webhook/webhook.js