Prevent default security group deletion.

This patch adds a check to confirm that a security group name
is not among a list of 'special' group names before proceeding
with security group deletion.

Fixes: bug 1131830

Change-Id: I5656e01b4ed3fd9c22abe6a731edaef7203d97c4
Merge "Prevent default security group deletion."
Merge remote-tracking branch 'm_src_repo/master' into build-temp