Migrate users from MD5 Hash system to Laravel without ask the users to change the password

gistfile1.php

<?php
// Try to log the user in.
if (Auth::attempt($userdata))
{
    // Redirect to homepage
    return Redirect::to('')->with('success', 'You have logged in successfully');
}
else
{
    $user = User::where('username','=',$userdata['username'])->first();
    if(isset($user)) {
        if($user->password == md5($userdata['username']."\n".$userdata['password'])) { // If their password is still MD5
            $user->password = Hash::make($userdata['password']); // Convert to new format
            $user->save();
            Auth::login($userdata['username']);
        }else{
            // Redirect to the login page.
            return Redirect::to('login')->withErrors(array('password' => 'Password invalid'))->withInput(Input::except('password'));
        }
    }
}