Add dynamic SEO metadata

[annakrystalli]

Look into using package django-meta.

• Create slugs for URLS
• Papers:
  • Detail & Edit: title: "{{Title}}", desc: "ReproHack Hub Paper by {{Authors}} submitted for review"
  • List: title: "ReproHack Paper List", desc: "Browse our central list of papers available for general review"
  • New: title: "Submit a paper", desc: "Submit a paper for reproducibility review to our ReproHack Hub"
• Events:
  • Detail: title: Title, descr: "ReproHack Event at {{date, time, tz}} in {{remote or city/country}}
  • List: title: "ReproHack Event List", desc: "Find an event near you!"
  • New: title: "Submit an Event", desc: "Submit your own ReproHack event to our ReproHack Hub"
• Reviews: Title: title
  • New: title: "Submit a Review", desc: "Submit a reproducibility review to our ReproHack Hub"
  • List: title: "ReproHack Review List", desc: "Browse the list of public submitted reviews"
• All markdown pages: title: page_title, desc: first sentence of page?