Add Danger

[dannytce]

https://github.com/danger/danger-js

You can:

• Enforce CHANGELOGs
• Enforce links to Trello/JIRA in PR/MR bodies
• Enforce using descriptive labels
• Look out for common anti-patterns
• Highlight interesting build artifacts
• Give warnings when specific files change

There is also this loveliness: https://github.com/danger/peril