Stacker

- Fix typo in RDS base blueprint introduced in GH-29 [GH-44]

This is the first release to include blueprints with the new Blueprint Variables
concept introduced in stacker 0.8.

- output EmpireMinionRole [GH-18]
- allow users & groups for firehose [GH-19]
- KMS integration for firehose [GH-20]
- Update empire stacks to use Empire Daemon [GH-22]
- Add test helper for empire stacks [GH-26]
- Allow use of existing security group with RDS [GH-29]
- Move to compatible release versions for all dependencies [GH-30]
- Add SNS, SQS, DynamoDB Blueprints [GH-43]

- Fix issue w/ firehose support relying on unreleased awacs features

- Make internal zone first in DNS in VPC blueprints [7]
- Add support for NAT Gateways [10]
- Add stack to help creating firehose delivery streams [16]

- add `stacker dump` subcommand for testing stack/blueprints [GH-156]

- Allow users to override name of bucket to store templates [GH-145]
- Add support for passing environment variables on the cli via --env [GH-148]
- Cleanup output on non-verbose runs [GH-153]
- Added `compare_env` command, for easier comparing of environment files [GH-155]