Description of problem:
When resuming an upload that was auto-paused because of a browser refresh, the upload is paused again.

Version-Release number of selected component (if applicable):
2e39dce667aa4f432e699b4b453ddd2ae008221c

How reproducible:
100%

Steps to Reproduce:
1. Start an image upload via the UI.
2. After some progress, refresh the webadmin tab in tab browser.
3. Wait ~ one minute until the transfer is paused automatically and resume it manually.

Actual results:
After a few seconds, the transfer is paused again.

Expected results:
The transfer should continue.

Additional info:
From the engine log:
2017-11-21 11:48:39,147+02 INFO  [org.ovirt.engine.core.bll.storage.disk.image.TransferDiskImageCommand] (EE-ManagedThreadFactory-engineScheduled-Thread-19) [8039af12-b605-4444-b9de-bdc223fb7f1d] Transfer was paused by system. Upload disk 'RHEL-7.0-20140507.0-Server-x86_64-dvd1.iso' (id '00000000-0000-0000-0000-000000000000')

From the proxy log:
Thread-62 ) ERROR root:Failed: {"explanation": "The server could not comply with the request since it is either malformed or otherwise incorrect.", "code": 400, "detail": "Invalid content-range: 'bytes 542113792--1/0'", "title": "Bad Request"}
(Thread-62 ) WARNING web:ERROR [10.35.1.94] PUT /images/f61a1dff-9082-434f-b393-8dc0b2fb918a: [400] Failed response from host: {"explanation": "The server could not comply with the request since it is either malformed or otherwise incorrect.", "code": 400, "detail": "Invalid content-range: 'bytes 542113792--1/0'", "title": "Bad Request"} (0.01s)


From the browser log:
INFO: sendChunk: PUT https://ishaby1.tlv.redhat.com:54323/images/f61a1dff-9082-434f-b393-8dc0b2fb918a bytes 542113792--1/0
PUT https://ishaby1.tlv.redhat.com:54323/images/f61a1dff-9082-434f-b393-8dc0b2fb918a 400 (Bad Request)
Failed to load https://ishaby1.tlv.redhat.com:54323/images/f61a1dff-9082-434f-b393-8dc0b2fb918a: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://ishaby1.tlv.redhat.com:8080' is therefore not allowed access. The response had HTTP status code 400.
webadmin-0.js:19828 Tue Nov 21 11:48:20 GMT+200 2017 org.ovirt.engine.ui.uicommonweb.models.storage.UploadImageHandler
SEVERE: xhrHandle: Status: 0, text: , response: 
Tue Nov 21 11:48:20 GMT+200 2017 org.ovirt.engine.ui.uicommonweb.models.storage.UploadImageHandler
SEVERE: xhrError: 0 
Tue Nov 21 11:48:20 GMT+200 2017 org.ovirt.engine.ui.uicommonweb.models.storage.UploadImageHandler
WARNING: xhrError: Retrying (attempt 1 of 3)

And after 3 attempts (browser log):

Tue Nov 21 11:48:29 GMT+200 2017 org.ovirt.engine.ui.uicommonweb.models.storage.UploadImageHandler
SEVERE: Transfer to proxy failed, code: 0, text: , response: 
Tue Nov 21 11:48:29 GMT+200 2017 org.ovirt.engine.ui.uicommonweb.models.storage.UploadImageHandler
WARNING: Finalizing upload with status CLIENT_ERROR
Tue Nov 21 11:48:29 GMT+200 2017 org.ovirt.engine.ui.uicommonweb.models.storage.UploadImageHandler
INFO: Updating status to Paused by System