Tweet when a new project/org installs the app with a welcome message

[rajatjindal]

today we do get a notification when a new project/org installs the app, but we ignore it. instead we should tweet the new installation with a welcome msg.

this gist has a sample request: https://gist.github.com/rajatjindal/b8d4347fc72e6275dc74151698ea4575

[rajatjindal]

I am almost done with the changes on my laptop. will test it before pushing and opening a PR.

[alexellis]

Hey you should be aware that installing the app can vary between a single repo, multiple repos or a whole org being added. They are different JSON events.