Added client string to configuration

Clients can set their own client string which will be send to connected
peers during the handshake.

ethutil/config.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"os/user"
 	"path"
+	"runtime"
 )
 
 type LogType byte
@@ -23,6 +24,7 @@ type config struct {
 	ExecPath     string
 	Debug        bool
 	Ver          string
+	ClientString string
 	Pubkey       []byte
 	Seed         bool
 }
@@ -48,6 +50,7 @@ func ReadConfig(base string) *config {
 
 		Config = &config{ExecPath: path, Debug: true, Ver: "0.3.1"}
 		Config.Log = NewLogger(LogFile|LogStd, LogLevelDebug)
+		Config.ClientString = fmt.Sprintf("/Ethereum(G) v%s/%s", Config.Ver, runtime.GOOS)
 	}
 
 	return Config

peer.go

@@ -7,7 +7,6 @@ import (
 	"github.com/ethereum/eth-go/ethutil"
 	"github.com/ethereum/eth-go/ethwire"
 	"net"
-	"runtime"
 	"strconv"
 	"strings"
 	"sync/atomic"
@@ -158,7 +157,7 @@ func NewOutboundPeer(addr string, ethereum *Ethereum, caps Caps) *Peer {
 		connected:   0,
 		disconnect:  0,
 		caps:        caps,
-		Version:     fmt.Sprintf("/Ethereum(G) v%s/%s", ethutil.Config.Ver, runtime.GOOS),
+		Version:     ethutil.Config.ClientString,
 	}
 
 	// Set up the connection in another goroutine so we don't block the main thread