move IP/Network lists to the data provider

this is a backward incompatible change, all previous file based IP/network
lists will not work anymore

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

main.go

@@ -21,8 +21,6 @@ package main // import "github.com/drakkan/sftpgo"
 
 import (
 	"fmt"
-	"math/rand"
-	"time"
 
 	"go.uber.org/automaxprocs/maxprocs"
 
@@ -34,6 +32,5 @@ func main() {
 		fmt.Printf("error setting max procs: %v\n", err)
 		undo()
 	}
-	rand.Seed(time.Now().UnixNano())
 	cmd.Execute()
 }