Build Sponsor page and Sponsor Block

[Kingdutch]

We need a sponsor page that shows the various levels of sponsorships. The Barcelona Sponsorpage can be used as example. The top levels should possibly also be shown on the frontpage.

To add sponsordata the content/sponsors/example.md can be copied.

The following GraphQL query can be used to select sponsordata in a view.

allSponsors: allMarkdownRemark(
    filter: { 
      fields: { collection: { eq: "sponsors" } },
      frontmatter: { hidden:{ne: true}}
    }
  ) {
    nodes {
      frontmatter {
        name
        link
        group
        level
        image { 
        	childImageSharp {
              fluid(maxWidth: 300) {
                  ...GatsbyImageSharpFluid
              }
          }
        }
      }
    }
  }