Backend: ACH management server

[aaronmboyd]

The system and app users need to know when Berkshares have been credited and ready to use.

• Polling server / on target FBO or omnibus account (check that ACH has settled and funds received in reserve account). There may not be a fully deterministic way to determine ACH settlement, as returns may occur. ACH Management Server: Polling service #26
• Handle NSF / ACH returns, probably go into a queue for manual reconciliation / customer support in lieu of a fully automated retry and fall-off system ACH Management Server - Handle ACH errors #27
• Mint the Berkshares, directly on-chain interaction with smart contract suite ACH Management Server: Polling service #26
• Burn the Berkshares, when redemption requested via interaction with smart contract suite ACH Management Server: Polling service #26
• (Implicit) Balance in BerkShares app updated accordingly, with a notification