New website layout!

[ninadicara]

We've just merged PR #112 which was a big restructure of the website.
It has added:

• Individual pages for each Data Hazard (this should mean they can be longer, and have contributor records for each page).
• More detailed contribution guidelines.
• Restructured our materials into a How to use guide.
• Added an About page with a cool image of the 'Anatomy of a Data Hazard label' :D

Hopefully this will all make it easier to use our resources and also for new people to get involved in the Data Hazards development!