Github PR to Slack Message per Yuichi

Adds a button and context menu to copy a Github pull request as a slack message you can post to your team.

Tired of copying the pull request title and link by hand and posting it in Slack?
Does your team not let you have Slack integrations for Github?
Do you hate the markup syntax?

This extension creates a beautiful Slack message with one button.

Copies a Slack message to your clipboard with:
- The organization and the repository name
- A link to the pull request with the title and id
- The description in block quotes