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 if can be set appropriately to nova/quantum.

Change-Id: If4fdb12cb9495ff39e8010be0665904b2a2966ce
Merge "Expose security_group_api for nova compute" into stable/grizzly