Modify the time sorter tests to make golint happy.
Modify the time sorter tests to make golint happy.

This commit changes the internal testing mechanism from returning the
unexported timeSorter type directly to insted returning sort.Interface.
This has been done because the latest version of golint complains about
return unexported types.

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