Add -L parameter to curl for download ISO files

Add -L parameter to curl for download ISO files

same as patch 24385, which just fixed the latest.properties file

curl:
   -L, --location
   (HTTP/HTTPS)  If the server reports that the requested page has moved
   to a different location (indicated with a Location: header and a 3XX
   response code), this option will make curl redo the request on  the
   new  place.

without -L, curl just download the redirects info not the file.

JIRA: FUEL-225

Change-Id: I20a01b628ca1545def68bd4e0b24594c24ee7f85
Signed-off-by: Julien-zte <zhang.jun3g@zte.com.cn>