add mulit keys save support

[synped-dev]

I see laravel not support mulit key save , this method may be resolve this problem

 protected function setKeysForSaveQuery($query)
   {
       $primary = $this->getKeyName();
       if(!is_array($primary)){
           $primary = [$primary];
       }
      $primary = (count($this->getKeyName()) > 1) ? $this->getKeyName() : [$this->getKeyName()];
      // Fetch the primary key(s) values before any changes
      $unique = array_intersect_key($this->original, array_flip($primary));
       // Fetch the primary key(s) values after any changes
       $unique = !empty($unique) ? $unique : array_intersect_key($this->getAttributes(), array_flip($primary));
       // Apply SQL logic
       $query->where($unique);
      //$query->where($this->getKeyName(), '=', $this->getKeyForSaveQuery());

       return $query;
   }