Create data hash folders during startup, too

So, that we are not constantly trying to mkdir() what is already there.
This is a small performance improvement.

handlers.go

@@ -197,7 +197,6 @@ func SaveBlob(c *Context) http.HandlerFunc {
 		}
 
 		if dir == "data" {
-			os.MkdirAll(filepath.Join(c.path, dir, name[:2]), 0700)
 			name = filepath.Join(name[:2], name)
 		}
 		path := filepath.Join(c.path, dir, name)

server.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"log"
 	"net/http"
 	"os"
@@ -29,6 +30,9 @@ func main() {
 	for _, d := range dirs {
 		os.MkdirAll(filepath.Join(*path, d), 0700)
 	}
+	for i := 0; i < 256; i++ {
+		os.MkdirAll(filepath.Join(*path, "data", fmt.Sprintf("%02x", i)), 0700)
+	}
 
 	// Define the routes.
 	context := &Context{*path}