PEAR Dropbox: merge upstream commit

- https://github.com/nao-pon/dropbox-php/commit/bc534c15144209ac2e6249f47fb2d568faf1b8ea
- https://github.com/nao-pon/dropbox-php/commit/65d3c0666a84de6176c2b69b91da79d5141b0318