Issue 17 bugs url

Adds a bugs url to the package.json to allow easy access to our GitLab issues.

This allows:

• npm bugs will now open the issues page in your default browser
• The npm page for our package should display a link to our issues

Closes #17 (closed) Closes https://gitlab.developers.cam.ac.uk/uis/devops/digital-admissions/admissions-portal/ap-frontend/-/issues/56