Implement output silencing, afterAll, and afterEach.

It's possible for calling code to do a few more things now.

- Silence all console output.
- Define an afterAll that executes after all commands are done.
- Define an afterEach that executes after each command is run.

These are primarily intended to facilitate tests.
Implement specs for executeDeployment method.
Throw errors if you try to define an invalid deploy job.
Update spec for deploy job to cover errors.
Catch errors while trying to load configuration files.