Support sending JSON

[robertjahn]

I have tried to send JSON with the Send Chat Message attachment section or the Upload File option. Perhaps there is just some syntax required, but what happens is I just see the left bracket of the json that I specify as an argument. I have tried with surrounding in triple back-ticks ``` too.

[robertjahn]

Note that I can get this to works for making an attachment, but I would like to view the json in the slack message so that I dont have to open the attachment In script task do this

set my json contents into a variable called Json - then save to a file in the release
Out-File -FilePath "$(System.DefaultWorkingDirectory)\mydata.json" -InputObject $Json
in the slack task upload argument
$(System.DefaultWorkingDirectory)/mydata.json