Stacker

- YAML & JSON codecs for `file` lookup [GH-537]
- Arbitrary `command` hook [GH-565]
- Fix datetime is not JSON serializable error [GH-591]
- Run dump and outline actions offline [GH-594]
- Helper Makefile for functional tests [GH-597]
- Python3 support!!! [GH-600]
- YAML blueprint testing framework [GH-606]
- new `add_output` helper on Blueprint [GH-611]
- Include lookup contents when lookups fail [GH-614]
- Fix issue with using previous value for parameters [GH-615]
- Stricter config parsing - only allow unrecognized config variables at the top-level [GH-623]
- Documentation for the `default` lookup [GH-636]
- Allow configs without stacks [GH-640]

- Support for provisioning stacks in multiple accounts and regions has been added [GH-553], [GH-551]
- Added a `--profile` flag, which can be used to set the global default profile that stacker will use (similar to `AWS_PROFILE`) [GH-563]
- `class_path`/`template_path` are no longer required when a stack is `locked` [GH-557]
- Support for setting stack policies on stacks has been added [GH-570]

The biggest change in this release has to do with how we build the graph
of dependencies between stacks. This is now a true DAG. As well, to
speed up performance we now walk the graph in a threaded mode, allowing
true parallelism and speeding up "wide" stack graphs considerably.

- assertRenderedBlueprint always dumps current results [GH-528]
- The `--stacks` flag now automatically builds dependencies of the given stack [GH-523]
- an unecessary DescribeStacks network call was removed [GH-529]
- support stack json/yaml templates [GH-530]
- `stacker {build,destroy}` now executes stacks in parallel. Parallelism can be controled with a `-j` flag. [GH-531]
- logging output has been simplified and no longer uses ANSI escape sequences to clear the screen [GH-532]
- logging output is now colorized in `--interactive` mode if the terminal has a TTY [GH-532]
- removed the upper bound on the boto3 dependency [GH-542]

- Fix parameter handling for diffs [GH-540]
- Fix an issue where SIGTERM/SIGINT weren't handled immediately [GH-543]
- Log a line when SIGINT/SIGTERM are handled [GH-543]
- Log failed steps at the end of plan execution [GH-543]
- Remove upper bound on boto3 dependency [GH-542]

The biggest change in this release has to do with how we build the graph
of dependencies between stacks. This is now a true DAG. As well, to
speed up performance we now walk the graph in a threaded mode, allowing
true parallelism and speeding up "wide" stack graphs considerably.

- assertRenderedBlueprint always dumps current results [GH-528]
- stacker now builds a DAG internally [GH-523]
- The `--stacks` flag now automatically builds dependencies of the given stack [GH-523]
- an unecessary DescribeStacks network call was removed [GH-529]
- support stack json/yaml templates [GH-530]
- `stacker {build,destroy}` now executes stacks in parallel. Parallelism can be controled with a `-j` flag. [GH-531]
- logging output has been simplified and no longer uses ANSI escape sequences to clear the screen [GH-532]
- logging output is now colorized in `--interactive` mode if the terminal has a TTY [GH-532]

- Add `blueprint.to_json` for standalone rendering [GH-459]
- Add global config for troposphere template indent [GH-505]
- Add serverless transform/CREATE changeset types [GH-517]