Refactors

Currently when users sends a POST to <endpoint>, we <describe endpoint behavior>. It would be better to split this endpoint into 2 separate endpoints because <explain reasoning>.
<Describe what the first endpoint should do>.
<Describe what the second endpoint should do>.
Test by <explain how Devin can test each endpoint to verify it's on the right track>.

In the slack server, refactor AppRegistry into its own file.