Separated the root synchronization operation into three different classes. One that does the download, once that does the sync, and once that does the upload.
Removed the unneeded Dropbox-based synchronization operation.
Put the Dropbox-based pre and post synchronization operations in place.
Rejigger the document sync manager to use the new synchronization operation triad.
Migrate the file manager-based sync operations to the new three-operation structure.
Ensure that the synchronization operation is thread-safe in regards to how it uses its managed object contexts.