Make xenapi fake match real xenapi a bit closer
Make xenapi fake match real xenapi a bit closer

xenstore_data is a dictionary in the real xenapi and keys get deleted
from xenstore_data and other_config when removing them instead of being
set to None.

Change-Id: I462b04b6e1dc5ad4abf05cc50538121811c2334e

n0ano/ganttclient