• client resets of HTTP/2 streams led to unwanted 500 errors
  reported in access logs and error documents. The processing of the
  reset was correct, only unneccesary reporting was caused.
• Upgrade requests from HTTP/1.1 to HTTP/2 via the "Upgrade" header were
  always ignored for a request with a body. The check for this was incomplete
  and missed bodies announced via "Transfer-Encoding". Fixed. Refs #243