Always use group_id when specifying security groups.

The AWS EC2 API does not accept the 'group_name' parameter when launching
instances into a VPC subnet and requires that the 'group_id' parameter
is used instead.

This changes results in 'group_id' always being used, regardless of
whether or not instances are launched in a VPC

ec2 module uses 'mutually_exclusive' construct for group and group_id
Include private IP and DNS info in module's response json
YAML requires quoting the entire value when it starts with a quote

Fixes #2280.