v2.0 is here with Bootstrap 4 and lot's of improvements

• Bootstrap is updated to version 4.
• Now also available as npm package vali-admin
• Page structure is updated
  • Sidebar and top navbar structure and styles are updated
  • CSS classes are now less specific
  • CSS classes are now named according to BEM
  • Styles are now written in SCSS
• Add search form in navbar
• Renamed existing card component to tile to avoid interference from newly introduced card component in Bootstrap 4