Replace chainec.Sign with secp256k1.SignCompact in SignMessge RPC (#258)
Replace chainec.Sign with secp256k1.SignCompact in SignMessge RPC (#258)

Fixes #248
jrick/dcrwallet,decred/dcrwallet,jrick/dcrwallet,jrick/btcwallet,decred/dcrwallet,jrick/btcwallet