Post approved public Kudos to Slack

[mkimberlin]

Describe the solution you'd like
I would like to see public, approved Kudos posted to the #kudos Slack channel

Describe alternatives you've considered
Alternatively, they could be managed as subscribable notifications and messaged to individuals directly. However, that is a heavier lift and the above solution would be a great initial step.

Additional context
Submitting public kudos:

Message should get posted to Slack on approval:

[ocielliottc]

@ocielliottc Need to investigate Gson reflection configuration.