ovirt-image-uploader: Provide more informative error messages
ovirt-image-uploader: Provide more informative error messages

The code was modified to provide more information on connection
failures, so now more specific information will be available to
users.

Also some error logic was added to process request errors,
that is errors that happen after the successful connection was
established, e.g. bad authentication etc. Now we can provide
specific messages based on the return code e.g. 401, 503 etc.

Change-Id: I66d8c6dc59169bdc798256bd2d150fbc8cda7665
Signed-off-by: Lev Veyde <32edd3ccb8e9d69e90ee9ce8dbc368c1f61bdf7b@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1182344

oVirt/ovirt-image-uploader,oVirt/ovirt-image-uploader,oVirt/ovirt-image-uploader