ensure unique file names are returned (#1239)
ensure unique file names are returned (#1239)

* ensure unique file names are returned 

// glob() can return the same file multiple times
        // This will cause the migration to fail with a 
        // false assumption of duplicate migrations
        // http://php.net/manual/en/function.glob.php#110340

* fix spacing issue

ikagawa/phinx,daniel-gomes-sociomantic/phinx,robmorgan/phinx