Issues with mined blocks on BTC regtest chain
### Description

Using MiningCore for BTC, on regtest chain, with 4 peers, seems to get only orphans, blocks are found easily but all of them become orphans on the app but they're credited on the bitcoin wallet, have tried using an ASIC S7, or CPU mining (minerd)

### Steps to Reproduce

1. Setup BTC regtest chain with 4 peers
2. Connect Clients on MiningCore.
3. Wait for blocks

### Expected behavior

Mine blocks to test payment processor.

### Actual behavior

All mined blocks are being orphaned on the miningcore, but credited on bitcoind

### Reproduces how often

All mined blocks

### Version

Docker version over a Ubuntu 16.04 instance

### Additional Information

```javascript
{
    "logging": {
        "level": "info",
        "enableConsoleLog": true,
        "enableConsoleColors": true,
        "logFile": "",
        "logBaseDirectory": "",
        "perPoolLogFile": false
    },
    "api": {
    	"enabled": true,
        "listenAddress": "0.0.0.0",
        "port": 4000
    },
    "banning": {
        "manager": "integrated",
        "banOnJunkReceive": false,
        "banOnInvalidShares": true
    },
    "notifications": {
        "enabled": false,
        "email": {
            "host": "smtp.example.com",
            "port": 587,
            "user": "user",
            "password": "password",
            "fromAddress": "info@yourpool.org",
            "fromName": "support"
        },
        "admin": {
            "enabled": false,
            "emailAddress": "user@example.com",
            "notifyBlockFound": true
        }
    },
    "persistence": {
        "postgres": {
            "host": "db",
            "port": 5432,
            "user": "miningcore",
            "password": "miningcore",
            "database": "miningcore"
        }
    },
    "paymentProcessing": {
        "enabled": true,
        "interval": 600,
        "shareRecoveryFile": "recovered-shares.txt"
    },
    "pools": [{
      "id": "btc-5",
      "enabled": true,
      "coin": {
        "type": "BTC",
        "algorithm": "sha256d"
      },
      "address": "2Mv82TfpVKo1m7QAKzGbLYfhB938QGxjUEJ",
      "rewardRecipients": [
        {
          "address": "2Mv82TfpVKo1m7QAKzGbLYfhB938QGxjUEJ",
          "percentage": 1
        }
      ],
      "blockRefreshInterval": 500,
      "jobRebroadcastTimeout": 10,
      "clientConnectionTimeout": 600,
      "banning": {
        "enabled": true,
        "time": 600,
        "invalidPercent": 50,
        "checkThreshold": 50
      },
      "ports": {
        "3062": {
          "listenAddress": "0.0.0.0",
          "difficulty": 4096,
          "varDiff": {
            "minDiff": 2048,
            "targetTime": 15,
            "retargetTime": 90,
            "variancePercent": 30
          }
        }
      },
      "daemons": [
        {
          "host": "bitcoindaemon",
          "port": 18400,
          "user": "bitcoin",
          "password": "bitcoin"
        }
      ],
      "paymentProcessing": {
        "enabled": true,
        "minimumPayment": 0.5,
        "payoutScheme": "PPLNS",
        "payoutSchemeConfig": {
          "factor": 2.0
        }
      }
    }]
}
```
