using "" account is non-functional

[ericecook]

the daemon RPC will successfully return a balance from using the "" account for getbalance, but sendmany apparently doesn't like it (at least the way it is currently passed).

This means using the account: "" will result in error messages which don't make sense, like this :

[apscheduler.scheduler] [INFO] Found 98.65110439 CANN balance in local wallet
[apscheduler.scheduler] [INFO] Account balance for CANN account 'None': 98.65110439
[apscheduler.scheduler] [INFO] Total to be paid 98.65110439
[apscheduler.scheduler] [ERROR] Payout wallet is out of funds!

[icook]

After looking at the code it seems like the most logical fix would be to add a relevant method to the CoinRPC wrapper, or move the account config out of the RPC config section. I'm leaning towards the latter since the connection object being account specific never really made much sense.