Fix two warnings
Fix two warnings

- Ruby does byte compare on strings, rather than codepoint compare, so
  normalize all dNSName strings to UTF-8 before comparing
- Intel AMT/vPro uses serverAuth certs with an extra EKU; don't warn on
  this EKU, instead provide an info message (Fixes #5)

awslabs/certlint,awslabs/certlint,awslabs/certlint