Fix for fileupload/dropbox and standard du options (for BSD/Mac OS)

- Upload url (jQuery.filedrop) is updated now on `location.change`.
- Proposal: the uploads list should not be emptied on `location.change`. The user might want to know if his upload failed/succeeded - even if he continues browsing other files

- Also two additions to `.gitignore` for PHP-/Webstorm and Mac users.

- Uses standard options for `du`. The former used `-b` option is not available on BSD (e.g. Mac OS) (See http://www.openbsd.org/cgi-bin/man.cgi?query=d or http://en.wikipedia.org/wiki/Du_(Unix))