This basically works, but there's a bug when renaming a file that leaves
a .git-annex-temp-content-key file in the webdav store, that never gets
cleaned up.
Also, exporting files with spaces to box.com seems to fail; perhaps it
does not support it?
This commit was supported by the NSF-funded DataLad project.
The benefit of using a compatable directory structure does not outweigh the
cost in complexity of handling the multiple locations content can be stored
in directory special remotes. And this also allows doing away with the parent
directories, which can't be made unwritable in DAV, so have no benefit
there. This will save 2 http calls per file store.
But, kept the directory hashing, just in case.
