large video encodings using CIFS network file system

[mgogoulos]

Just want to share some info on how we were able to get very large files (100GB) to be encoded, while the MEDIA_ROOT was pointing to a mounted path that was using CIFS.

The encoding phase would hang and eventually be failing. I noticed that at some point the md5sum check that is made takes too long, perhaps that's the case for large files, independent of whether they are on a local FS or a remote one.
On files.helpers.media_file_info I've skipped the part

    cmd = ["md5sum", input_file]
    stdout = run_command(cmd).get("out")
    if stdout:
        md5sum = stdout.split()[0]
    else:
        md5sum = ""

just replaced with md5sum = "" without running the command md5sum. I have also increased the time that the chunkize_media is allowed to run, and I'm also pushing this change through #1161 . In the 100GB file case through CIFS, that task actually took more than 1h to run!

With these two changes, the file was encoded in a few hours in all available formats