Upload OVF enhancement for known issues

[guo1017138]

This issue is for a fix track for the known issues for uploading OVF/OVA listed below. But this fix should be after pull request #323 merged.
Here is a working fix commit in my forked repo
guo1017138@9d57a8f

Any comments is welcome.

Issue list:

1. In some bad situation, such like user offered OVF file doesn't contains ovf:size for files. The error as below.
   Err: unhandled API response, please report this issue, status code: 416 Content-Range not satisfiable: Request invalid
2. If user's OVF has wrong ovf:size, in some condition, vCloud API returned 400 error without body, the error can't be populated correctly. It reports:
   Err: API Error: 0:
   But real response like below which body part is empty:
   Status:400 Client sent more data than expected StatusCode:400 Proto:HTTP/1.1 ProtoMajor:1 ProtoMinor:1 Header:map[Content-Length:[0]] Body:0xc00041c500 ContentLength:0 TransferEncoding:[] Close:false Uncompressed:false Trailer:map[] Request:0xc0003c8800 TLS:0xc00042c2c0
3. If I call ShowUploadProgress to show progress, it may go into infinity loop and never return.
   Known triggers:
   • The upload task was cancelled by user on GUI or any error occur during show upload progress
   • ovf:size is not correct for vmdk. (rainy day case, may never match 100.00)