EC2 VPC security group updates - EUCA-9608

Security groups are updated for VPC support. VPC security groups allow
all protocols (0-255) and rules for any protocol (-1). The permitted
characters in VPC security group names and descriptions are different
from non-VPC security groups. VPC security groups can only reference
other groups in the same VPC. The default security group in a VPC cannot
be deleted.

EUCA-9608
EC2 VPC security group egress rule support - EUCA-9611

NetworkRule now includes a flag to denote egress/ingress rules. Egress
authorize/revoke actions are implemented and egress rules are included
when describing security groups.

EUCA-9611
Unit tests updated for security group changes - EUCA-9611