Stackmanager

* __Breaking change__: `--config` option changed to `--config-file` (short version is still `-c`)
* 19 Implement chaining between commands with support for calling `build-lambda -> upload -> deploy` with reduced arguments
* Allow `--profile` and `--region` to be specified before subcommands
* Testing for the CLI module

* Add support for `Variables` in configuration that can be substituted into `Parameters`, `Tags` and `StackName`.

* Add `status` command to check current status of stack
* Display output from `build-lambda` command
* Significantly improved code coverage (but still work to do)

* Add `reject` command to delete a ChangeSet and clean up the stack if it's in REVIEW_IN_PROGRESS and has no remaining ChangeSets.

Bugfix: Add missing arrow library to package

* Improve formatting of timestamps and the reason in the table of events. Use the `STACKMANAGER_TIMEZONE` environment variable to specify the timezone for timestamps to be shown in instead of the automatically detected local timezone (which may be UTC on a build server).