md5sum on uploaded videos before moving them from temporary directory

[KyleMaas]

Describe the issue
I think this is part of the cause of #852. I noticed the other day when MediaCMS was processing an upload, it was running an md5sum on the uploaded video before it responded to the client with a success message. In tracking this down, it looks like this is being done here:

mediacms/files/helpers.py

Line 273 in c5047d8

cmd = ["md5sum", input_file]

And going up the call stack:

mediacms/files/models.py

Line 459 in c5047d8

ret = helpers.media_file_info(self.media_file.path)

mediacms/files/models.py

Line 430 in c5047d8

self.set_media_type()

Which I think is coming from here:

mediacms/files/models.py

Line 1373 in c5047d8

instance.media_init()

For those of us with large slow primary video data storage but fast /tmp on a tmpfs, this really should be happening locally on the server processing the upload rather than making the uploading client wait for it to go to the slow disk and then be read back again for the md5sum.

To Reproduce
The impact of this is not particularly noticeable unless you're processing huge video files and your storage is slow, so this may not be easy to duplicate without uploading videos >1 hour long. However, if you can set up the conditions correctly:

1. Upload a long video - at least an hour
2. In a separate window, open a terminal and watch ps or top for an md5sum command
3. Notice that this happens very early in the process

Expected behavior
The md5sum should be calculated on the uploaded file before being moved from /tmp to primary storage.

Screenshots
N/A

Environment (please complete the following information):

• OS: Ubuntu Linux
• Installation method: Single server install
• Browser, if applicable: N/A

[KyleMaas]

mediacms/uploader/views.py

Line 68 in c5047d8

new = Media.objects.create(media_file=myfile, user=self.request.user)