[BUG] Repeating file send if it's already existing in the cache

[rabits]

Issue description:

Addon tries to resend the file if the Manager is already answered with 200 HTTP code and closed the connection. It will continue in 3 retries, so not a critical one, but time-consuming.

Environment:

• Application version: 0.2, 0.3.1
• Blender client version: 2.83.6
• OS: at least Windows

Steps to reproduce:

1. Run Blender
2. Open test-project
3. Connect to any Manager
4. Click on Run Animation Tasks button
5. Check the Addon Blender log - it will contain repeats for the project file, for example

Expected behavior

The Addon should check the return code of the put command (Client.taskFileStreamPut() usually) - probably windows generates some exception there if the channel is closed.

[rabits]

I think there should be a way to send the headers first, check for close connection and if it's not closed - send the data. That will allow to be suer the connections is not just closed for some reason, but was closed because of the server already have the required file.

The other solution could be to request HEAD if the file available - but this will require a couple of requests to send the file.

For now the data will be sent anyway (at least some part of it)...

[rabits]

Seems this issue is not good after all on Windows platform when you running Run Animation Tasks. So fix in #88 looks works well and you can use it for now, but this bug needs a better solution after all.