Downloading docker images does not work on Windows

Changing build/download/docker_downloader.py to connect
docker engine in more default way i.e. taking engine
parameters from environment fixes this script.

Issue-ID: OOM-2223

Signed-off-by: Samuli Silvius <s.silvius@partner.samsung.com>
Change-Id: Iddf69593bb4cf4596e713c8d537a90424c5925ef
1 file changed