Link the user to a project's GIthub repo when joining a project channel

[atticoos]

When a user joins a channel, butler should message the user with a link to the project on Github and any other information.

Ideally, Butler should message the user in the channel itself, but only be visible to the channel. Slackbot does this, I hope that any bot can do this.

Otherwise, we can just DM them with the bot