enable deleted files

currently it is impossible to list and work with deleted files through this API (it returns null if it encounters a deleted file)
I've made some changes to be able to work with deleted files too (see changes) and tried to provide a compatible version for applications based on the current API's methods.

This is my first pull request and I did not plan to be one as I forked the repo -- this is why there are so many commits. And my eclipse messed a bit around with the code formatting.

cheers
Gabor