Front End Enhancements

• [all pages] footer and link to contribution page
• [new page] contribution page
• [catalog page]
  • search box expansion
  • model/dataset filter
  • sort options
  • pagination
• [item page]
  • downloaded by
  • download counts
  • (download count and downloaded by data - fetch via API parameterized by item id)
  • change download link to redirect to unicef inform page first before download
  • use link alt-format property to group together download links
  • separate name and description in link dataset description