Bump default user agent to 0.2.0.
Bump default user agent to 0.2.0.

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