Define deploy settings in yml

**Is your feature request related to a problem? Please describe.**

Excuse me if I am missing something here, but I find it quite error-prone having to type the deploy bucket name, the region as well as the CloudFormation stack name each time I want to deploy/update an application. Except for being slightly time-consuming, a small typo might lead to creating a new stack instead of updating an existing one.

**Describe the solution you'd like**

The deploy parameters should be included in the .yml configuration file.

The issue names only a .yml configuration file; begin by locating the deployment command and configuration handling for the bucket, region, and CloudFormation stack name. Done means those values can be defined in YAML and reused for deploy or update without re-entering them; no specific files or tests are identified in the issue.

Written by the indexing model from the issue text.