Security groups support, no VPCs

Hi,
I have added following commands to the gem:

    knife ec2 security group list
    knife ec2 security group create -N name -D description
    knife ec2 security group delete -G group-id
    knife ec2 security group rule add -G group-id -P [tcp|udp|icmp] [-C cidr | -T target-group-id] -R [port|from-to]
    knife ec2 security group rule delete -G group-id -P [tcp|udp|icmp] [-C cidr | -T target-group-id] -R [port|from-to]

There's no VPC support.

Example output:

    tron:~ rad$ knife ec2 security group create -N "RadsTest" -D "RadsTest"
    Name: RadsTest
    Description: RadsTest
    Group ID: sg-d7ab12a0
    tron:~ rad$ knife ec2 security group rule add -G sg-d7ab12a0 -P tcp -C '0.0.0.0/0' -R 3000-4000
    Name: RadsTest
    Description: RadsTest
    Group ID: sg-d7ab12a0
    tron:~ rad$ knife ec2 security group rule delete -G sg-d7ab12a0 -P tcp -C '0.0.0.0/0' -R 3000-4000
    Name: RadsTest
    Description: RadsTest
    Group ID: sg-d7ab12a0
    tron:~ rad$ knife ec2 security group rule delete -G sg-d7ab12a0 -P tcp -C '0.0.0.0/0' -R 3000-4000
    Name: RadsTest
    Description: RadsTest
    Group ID: sg-d7ab12a0
    tron:~ rad$ knife ec2 security group delete -G sg-d7ab12a0
    tron:~ rad$