MultiPoolMiner does not report dual mining hashrate

[Richard]

The forked MultiPoolMiner only reports the first hashrate in a dual mining setup (Claymore). The second hashrate can be seen on the miner and MultiPoolMiner's status output, but not in MiningPoolHubStats.

This is not caused by the mismatched pools seen in the attached screenshot - dual mining Ethereum and Sia on MiningPoolHub is also affected.

[James Dimitrov]

Fixed #188

→ <<cset fc89fa258e53>>