Add import_packages script

This script can import Product, Package, Image, data,
and build the relationship between them.
All of the data is got from download.tizen.org.

Fixes: #1964
Change-Id: I7b64be43a8b8cb0e0ec4be4ab86509dd1a6b7fca
Signed-off-by: gaoxuesx <xuesongx.gao@intel.com>
Add downloading Tizen snapshots script

It dowdloads packages images trees informations from Tizen org,
then calls import_packages script to import data into IRIS.

Change-Id: Icbce3b731a9900af94bf0f6e699a153bef5c1843
Signed-off-by: gaoxuesx <xuesongx.gao@intel.com>