[2.0] Temporary file saving during import and syncing

@philipqueen I noted in #868 with the importing and syncing that there's a temporary directory being created to house the raw videos while they're being synced. The folder gets removed open successful importing, but question - if the import fails, or the software crashes, does that mean that there might be a folder with the raw videos somewhere in the users temp folder?

If so, what's the best way to handle that? Given the size that some video sessions become, I wouldn't want to accidently and silently contribute extra GB in video file sizes to their disk.