update.py: handle change to cooker structure in newer BitBake
update.py: handle change to cooker structure in newer BitBake

The cooker module has been refactored in BitBake master and this moved
and renamed the _parse() function; change the update script to handle
that (whilst still handling older versions).

Signed-off-by: Paul Eggleton <737d4dae46a541673d7bf4e0d5b32714b16528d8@linux.intel.com>

bartosh/layerindex-web,bartosh/layerindex-web,bartosh/layerindex-web