A simple gem to convert JIRA markdown into Slack markdown. You can find the gem here.
There is only one method, convert which accepts a string (which should be JIRA markdown) and returns a string (which will be Slack mardown).
JiraToSlack.convert("-This line is totally crossed out-")
=> "~This line is totally crossed out~"I'm sure there are more cases I've missed, but hey, maybe I'll get around to working on this a bit more, again.