Add permessage-deflate WebSocket support (RIPD-1409):

This also fixes a defect where the Server HTTP header was
incorrectly set in WebSocket Upgrade handshake responses.

src/ripple/rpc/impl/ServerHandlerImp.cpp

@@ -830,6 +830,7 @@ to_Port(ParsedPort const& parsed, std::ostream& log)
     p.ssl_cert = parsed.ssl_cert;
     p.ssl_chain = parsed.ssl_chain;
     p.ssl_ciphers = parsed.ssl_ciphers;
+    p.pmd_options = parsed.pmd_options;
 
     return p;
 }