recreating navbar for #24:
  - changed main css colors and organization
  - now using brands from db, corrected getNavbarBrands for the occasion
  - use a fixed-top navbar, coz it's so cool!
  - TODO: add categories from db
now using latest bootstrap v3.1.1, closes #25
added categories in dropdown menu, #24
added html option to link_to
corrected refresh navbars to keep all the categories
finished navbar with submenus, closes #24