Improve competition navigation

[dchaib]

The goal is to improve the navigation in the website to make new forecasts and/or view current classifications easier and faster, especially on mobile devices. The main problem is that the edition detail page is too complex.

• Only display current competitions in menu
• Move the classifications of the edition detail page into dedicated pages
• Add a secondary navigation bar linking to the newly created pages and the "most relevant" day
• Enable navigation between days (via a dropdown or prev/next buttons)
• Change the content of the edition detail page to:
  • The results of the last fixtures (score and user points)
  • The next fixtures (user forecasts)
  • A light user classification
• Add a page for archives