Small BelongsToMany tweak

src/Jenssegers/Mongodb/Model.php

@@ -221,12 +221,13 @@ abstract class Model extends \Illuminate\Database\Eloquent\Model {
         $instance = new $related;
 
         $otherKey = $otherKey ?: $instance->getForeignKey() . 's';
+
         // If no table name was provided, we can guess it by concatenating the two
         // models using underscores in alphabetical order. The two model names
         // are transformed to snake case from their default CamelCase also.
         if (is_null($collection))
         {
-			$collection = snake_case(str_plural(class_basename($related)));
+            $collection = $instance->getTable();
         }
 
         // Now we're ready to create a new query builder for the related model and