Fix consensus on private contract failure.

[joelburget]

Previously we had populated the public receipt failed field with the
result of the transaction. This is correct for public transactions. It's
also correct for successful private transactions. But it's not correct
for failing private transactions, because their public receipt should
not indicate failure. The fix is straightforward.

Testing:

I used this contract:

contract RevertTest{
   uint public newValue;
   function revertFunction() public{
       uint a = 1;
       require(a == 0);
   }
}

After deploying the contract I sent in several failing transactions via

function sendBad() {
  eth.sendTransaction({
  from: eth.accounts[0],
  data: web3.sha3("revertFunction()"),
  gas: 0x47b760,
  privateFor: ["ROAZBWtSacxXQrOe3FGAqJDyJjFePR5ce4TSIzmJ0Bc="]
  });
}

Watching the logs (1.log and 2.log), I saw the TX-ACCEPTED events
scroll as I sent revertFunction transactions. I see 10 TX-ACCEPTED
events in both logs (1 for deploy and 9 tests via sendBad).

Via extra logging, in 1.log I see that the public receipts have status
1, whereas private receipts have status 0. In 2.log they all have
status 1.

All nodes stayed up the whole time.

Fixes #434

[AldelopiomicA]

I can confirm, this PR fixed my problem. Both the test I've described in the issue #434, and so far so good in my developing project. (There is no Quorum node crash so far)