Users are unable to get a response out of Slab because it's not accepting any messages

[TylerConlee]

nginx configuration: {color:#14892c}good{color}
Slack configuration: {color:#14892c}good{color}
nlopes/slack: {color:#d04437}error{color}

DEBU[2019-11-21T22:13:33Z] Incoming Slack event                          event="{latency_report 0xc4203cc470}" module=slack
DEBU[2019-11-21T22:13:50Z] Incoming Slack event                          event="{user_typing 0xc4219d9140}" module=slack
DEBU[2019-11-21T22:13:51Z] Incoming Slack event                          event="{unmarshalling_error RTM Error: Could not unmarshall event \"message\": {\"client_msg_id\":\"7c8b914a-43b5-4d51-8f76-a459d2dfa07b\",\"suppress_notification\":false,\"type\":\"message\",\"text\":\"Test\",\"user\":\"U0A6UN7PA\",\"team\":\"T0A6UN7NU\",\"blocks\":[{\"type\":\"rich_text\",\"block_id\":\"uhNh\",\"elements\":[{\"type\":\"rich_text_section\",\"elements\":[{\"type\":\"text\",\"text\":\"Test\"}]}]}],\"user_team\":\"T0A6UN7NU\",\"source_team\":\"T0A6UN7NU\",\"channel\":\"C0A6V20SX\",\"event_ts\":\"1574374431.010500\",\"ts\":\"1574374431.010500\"}}" module=slack

Slack changed their API responses to support WYSIWYG.
https://api.slack.com/changelog/2019-09-what-they-see-is-what-you-get-and-more-and-less

This, in turn, broke Slab's ability to read the messages for Slab commands. More on this to come

[TylerConlee]

Resolved in #447