CSV: Add ability to set fee and change address

format:
fee, (fee in BTC)
change, (change address)

if there are more than one rows with the change or fee on it, it will
become the one on the bottom. (it will overwrite the previous one)

This is another small fix I made for myself. Reject if not deemed useful or necessary. I noticed that while you can set a fee with the send box, you could not specify a fee with csv input. It would automatically place the fee in your preferences even if you wanted to pay more.

I did not add any overt notifications, but rather figured anyone using such a feature would probably be someone that looks at the code anyways. If some notification of the fee and change ability to the user seems necessary I can add that in.