Fix #118, failed commands send error event message

[havencarlson]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution
Fix #118 , an error event message is sent if a command is not successful

Testing performed
Ran unit tests

Expected behavior changes
Behavior Change: All commands now send an error event message if unsuccessful

System(s) tested on
OS: Ubuntu 18.04

Contributor Info - All information REQUIRED for consideration of pull request
Haven Carlson - NASA

[github-advanced-security]

Found 11 potential problems in the proposed changes. Check the Files changed tab for more details.