feat(lib): add support to disable tokio-proto internals

For now, this adds `client::Config::no_proto`, `server::Http::no_proto`,
and `server::Server::no_proto` to skip tokio-proto implementations, and
use an internal dispatch system instead.

`Http::no_proto` is similar to `Http::bind_connection`, but returns a
`Connection` that is a `Future` to drive HTTP with the provided service.
Any errors prior to parsing a request, and after delivering a response
(but before flush the response body) will be returned from this future.

See #1342 for more.

src/proto/mod.rs

@@ -19,6 +19,7 @@ pub use self::chunk::Chunk;
 mod body;
 mod chunk;
 mod conn;
+pub mod dispatch;
 mod io;
 mod h1;
 //mod h2;
@@ -146,6 +147,8 @@ pub trait Http1Transaction {
     fn parse(bytes: &mut BytesMut) -> ParseResult<Self::Incoming>;
     fn decoder(head: &MessageHead<Self::Incoming>, method: &mut Option<::Method>) -> ::Result<h1::Decoder>;
     fn encode(head: MessageHead<Self::Outgoing>, has_body: bool, method: &mut Option<Method>, dst: &mut Vec<u8>) -> h1::Encoder;
+
+    fn should_error_on_parse_eof() -> bool;
 }
 
 pub type ParseResult<T> = ::Result<Option<(MessageHead<T>, usize)>>;