add a custom header clients can use to skip a n additional propset request
send back 'X-OC-MTime: accepted' when X-OC-MTime was applied
readd renaming and mtime handling to new directory nodes
also rename file when it has not been present before
check Content-Length to detect aborted uploads
delete partial file when file upload is aborted
only check content lenght on PUT to make litmus happy
Merge pull request #1596 from owncloud/fix_470

webdav put improvements