Include amounts with insufficient funds errors.
Include amounts with insufficient funds errors.

Closes #102.

Stash-Crypto/btcwallet,jrick/dcrwallet,Roasbeef/btcwallet,btcsuite/btcwallet,synrg-labs/btcwallet,btcsuite/btcwallet,Roasbeef/btcwallet,decred/dcrwallet,Stash-Crypto/btcwallet,jrick/btcwallet,decred/dcrwallet,jrick/dcrwallet,jrick/btcwallet,synrg-labs/btcwallet