Expose security_group_api for nova compute

This is already done for control node nova config, turns out
its needed for computes. This commit should take care of exposing
parameter so it can be set appropriately to nova/neutron.

Change-Id: I95a6e9e49cc14c4d5f390b271b60b5aaf2ea2278
Merge "Expose security_group_api for nova compute"