Implement functional testing

[gesparza3]

In order to be confident that new contributions did not break existing functionality, we should implement functional testing against Gratibot. This should include checks against a command(s) to verify:

• Gratibot responds to messages
• Database functionality is intact
• Correct config values are set(emoji values, exempt users, etc.)

[gesparza3]

Need a slack test account to be able to send test messages Gratibot can respond to in dev