Whent trying to upload/rename/create files in a folder that was removed
or rename, the correct error message is now shown.
In the case of upload of multiple files, the upload is cancelled.
This situation can happen if the target folder was renamed or removed
from another browser window or client.
When accessing a shared folder, the folder's owner appears as mountpoint
but wasn't wrapped by a quota storage wrapper.
This fix makes sure that all home storages are wrapped by a quota
storage wrapper, if applicable, to make sure quotas are respected when
uploading into shared folders.