• merged pull request from Tatsuhiro Tsujikawa, removing code for CONTINUATION
  frames that are never seen by mod_h2
• request/response headers are filtered when converting between HTTP/1.1 and
  HTTP/2 where they can only do harm (Expect/Connection/etc.)
• added test cases for uploads
• fixed handling of uploads ;-)
• enabled h2c upgrade for "OPTIONS *" requests
• changed h2_stream_set implementation to use sorted apr array
• switched to nghttp2 v0.7.7 in sandbox