H2 headers must be lower case

src/error.rs

@@ -1,3 +1,4 @@
+use http;
 use std::{error, fmt, io};
 
 /// The error type for HTTP/2 operations
@@ -162,6 +163,13 @@ impl From<ConnectionError> for io::Error {
     }
 }
 
+impl From<http::Error> for ConnectionError {
+    fn from(_: http::Error) -> Self {
+        // TODO: Should this always be a protocol error?
+        Reason::ProtocolError.into()
+    }
+}
+
 impl fmt::Display for ConnectionError {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         use self::ConnectionError::*;