Upgrade server dependencies, manage them with govendor

vendor/github.com/spf13/pflag/golangflag.go

@@ -6,13 +6,10 @@ package pflag
 
 import (
 	goflag "flag"
-	"fmt"
 	"reflect"
 	"strings"
 )
 
-var _ = fmt.Print
-
 // flagValueWrapper implements pflag.Value around a flag.Value.  The main
 // difference here is the addition of the Type method that returns a string
 // name of the type.  As this is generally unknown, we approximate that with