Cryptocurrency URI Links

[jonaharagon]

The cryptocurrency donation addresses should link to a payment URI.

• Bitcoin: https://bitcore.io/api/lib/uri
• Monero: https://github.com/monero-project/monero/wiki/URI-Formatting

Ethereum seems to be working on "ICAP" which is similar but may not be finished: https://github.com/ethereum/wiki/wiki/ICAP:-Inter-exchange-Client-Address-Protocol