Merge pull request #192 from ilesinge/belongstomany_sync

Backport Eloquent BelongsToMany::sync function signature

src/Jenssegers/Mongodb/Relations/BelongsToMany.php

@@ -47,7 +47,7 @@ class BelongsToMany extends EloquentBelongsToMany {
 	 * @param  bool   $detaching
 	 * @return void
 	 */
-	public function sync(array $ids, $detaching = true)
+	public function sync($ids, $detaching = true)
 	{
 		if ($ids instanceof Collection) $ids = $ids->modelKeys();