Fully working version (plus request to make me a co-maintainer)

Please find attached a fully working version of this module. Based on your alpha version, that only uploads to Dropbox, I added support for:
- the .info files
- list files
- delete file
- download file
- restore file

In short: a fully working destination that implements all options a destination can implement. This code is running for some time at my own sites and works as intended.

I am willing to support this code. That is, if you commit and release this code and make me co-maintainer, I will watch and respond to the issue queue. (If you make me co-maintainer based on a review of the code in the zip, I can also commit and release it myself.)

Note: as the changes and additions are massive, a patch would be larger )and less clear) then just the complete code itself. So I attached just a zip of the complete directory, not a patch.