Add exit codes for failed commands

[Xemdo]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Problem/Feature

Addresses #239 by adding exit codes for all failed commands.
This also adds in exit codes to twitch api, which will return exit code 1 when an API returns a non-2xx status code.

All errors will print to stdout to make it consistent across the entire program. Different features present data in different ways for different reasons, and it would take a rework of most things to write it in a way that print errors to stdout.
For example, twitch api get users will return a non-zero error code (because it returned a 400) but it will still write the JSON output to stdout instead of stderr.

Description of Changes:

• Added non-zero exit codes to all failed commands

Checklist

• My code follows the Contribution Guide
• I have self-reviewed the changes being requested
• I have made comments on pieces of code that may be difficult to understand for other editors
• I have updated the documentation (if applicable)