[enhancement] support Zcash as currency

[daira]

Brief Description: Zcash is a Bitcoin-like cryptocurrency that uses zero-knowledge proofs for anonymity: https://z.cash

The launch of the actual currency is planned for September 2016 but there's currently a testnet. The Zcash developers would be happy to help with any queries you have about supporting Zcash in OpenBazaar -- please ask on our Slack channel (I know that some OpenBazaar people are already there). You would probably need our high-level payment API which is not implemented yet, but is planned for August.

Operating System (OS and version): all
OpenBazaar version (shown on About OpenBazaar page in menu): future
Hardware: all

[daira]

Hmm. Perhaps this should have gone in the server repo. I guess it affects both the client and server. Feel free to move it if it should go elsewhere.

[daira]

OpenBazaar's moderator functionality requires multisig, which isn't directly supported by Zcash for anonymous transactions, but there are workarounds: zcash/zcash#782