Implement SendToAddress.
Implement SendToAddress.

Closes #56

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