Add the flag to override with original transaction data (but higher gas price)

Currently plunger can only wait for transactions to get mined or forcefully override them with zero-Ether transfer transactions (the --override-with-zero-txs flag). What I would like to see in addition to that would be a --override-with-original-txs flag which would make plunger use original calldata and value, just sign it again with higher gas price.