Begin using btcws.
Begin using btcws.

This change adds support for the unmarshaling custom commands sent by
btcwallet and supported in the btcws package.

dajohi/btcd,ppcsuite/ppcd,btcsuitereleases/btcd,jcmincke/dcrd,dajohi/btcd,sysbot/btcd,dan-da/btcd,Evil-Coin/Evil,jimmysong/btcd,adiabat/btcd,ltcsuite/ltcd,davecgh/btcd,dajohi/btcd,pkothbauer/btcd,stevenroose/btcd,FactomProject/btcd,qchain/btcd,DanielKrawisz/btcd,decred/dcrd,ppcsuite/ppcd-old,btcsuitereleases/btcd,pkothbauer/btcd,jcmincke/dcrd,jongillham/btcd,mathiasrw/btcd,Dirbaio/btcd,cjepson/btcd,jrick/btcd,qchain/btcd,Dirbaio/btcd,hectorj/btcd,danoctavian/btcd,dan-da/btcd,glv2/ppcd,CryptocurrencyCabal/htcd,Evil-Coin/Evil,cqswxj2013/btcd,DanielKrawisz/btcd,toddfries/btcd,jrick/dcrd,FactomProject/btcd,adiabat/btcd,sysbot/btcd,glv2/ppcd,jrick/btcd,runeaune/btcd,wallclockbuilder/btcd,btcsuite/btcd,runeaune/btcd,tb00/btcd,cjepson/btcd,wallclockbuilder/btcd,jrick/dcrd,btcsuite/btcd,ppcsuite/ppcd,BitGo/prova,danoctavian/btcd,jrick/btcd,1d4Nf6/btcd,jcmincke/dcrd,jimmysong/btcd,soapboxsys/ombfullnode,1d4Nf6/btcd,Dirbaio/btcd,decred/dcrd,soapboxsys/ombfullnode,CryptocurrencyCabal/htcd,jongillham/btcd,tb00/btcd,Roasbeef/btcd,BitGo/prova,hectorj/btcd,Cleawing/btcd,stevenroose/btcd,Stash-Crypto/btcd,Stash-Crypto/btcd,aakselrod/btcd,Roasbeef/btcd,ppcsuite/ppcd-old,cqswxj2013/btcd,aakselrod/btcd,mathiasrw/btcd,davecgh/btcd,ltcsuite/ltcd,Cleawing/btcd,toddfries/btcd