Multiple outputs

Feature branch completed the following:
- Changed YAML structure to create notion of 'targets'
- Modified Ruby code to hydrate Output and JobStream classes with new YAML contents
- Added "foo_email.yaml" as an example of new YAML format
- Added new entries in "addresses.yaml" to accommodate DEV testing

TODO:
- Create FileFilter base class
- Identify the set of 'targets' that satisfy requirements
- Extend FileFilter class for each of the identified 'targets'