Transaction states: stalling spike

[ryancreatescopy]

Closely related to #83

This issue pertains to the transaction state work we've been looking into.

We need to figure out:

• can we detect when a transaction has stalled e.g. not been picked up after 30 seconds? This is usually because the user has edit the gas price too low and no miner wants to pick up the Tx.

MetaMask offers the user the option to "speed up" said transaction... which I believe resubmits the transaction with the same `nonce` in the hope it will be confirmed quicker than the previous stalled transaction which will then fail because the `nonce` will be invalid.

• Can we offer this functionality in the dApp and send it to the wallet? E.g. can we tell the user their Tx has stalled and give them the option to increase the Tx fee (either within the dapp or deep link the user into the relevant area of the wallet UI where they can resubmit the transaction).
• Can a dApp detect when the Tx in question has been resubmitted so we can communicate that information back to the user in the dApp interface?

Alternatively...

• Is there a way we can detect if the user has edited the gas price to such an extent that it puts their Tx at risk of stalling/failing. And try and intercept them with a warning e.g. "Your transaction fee might not be enough to complete your transaction. We recommend increasing it"