Added new block callback parameters to upload methods (including chunking).

* Added uploadedFile to upload callback to provide full Dropbox path. Useful for passing along to getting sharable link.
* Added uploadID to chunked file upload callback.
Added default parameter names to all blocks to make for pleasant XCode autocompletion.
Merge pull request #1 from ZaBlanc/master

Fix-up the real-world use of file uploading, normal and chunked.