Set unique hostnames via Chef using the stack name and EC2 instance ID

Summary:
[cloudformation] add signifyd-base to platform template run list

[cloudformation] set chef node name using stack name and instance id

add signifyd-base to role[signifyd-platform] run list

[cloudformation] use entire instance id in chef node name

Test Plan: Build platform stacks, verify hostname is set, verify new hostname visible in papertrail

Reviewers: blaskey

Reviewed By: blaskey

Differential Revision: http://phab.signifyd.com/D481