Add 'Incomplete' to the getStats table

[lsaether]

Depending on the network conditions, a transaction may not get mined for a while and time out with the error:

Error: Transaction was not mined within 50 blocks, please make sure your transaction was properly send. Be aware that it might still be mined!

Since this is a soft error, it usually just means that the transaction will process successfully later. But this messes with the .getStats feature which uses the return receipt to track when a transaction was claimed or executed. We can add an 'Attempted' and/or 'Incomplete' column to the table to reflect that a transaction was sent but didn't complete successfully.