Import http routes from Cloud Hypervisor project

Import vmm/src/api/http.rs from Cloud Hyerpvisor project, commit
345c922cb9a88183e2da9d29230ecb945b0a6452 with following changes:
1) use generic type for handler argument.
2) remove server thread relative code.
3) add unit test cases.
4) refine for better code reuse.

Signed-off-by: Liu Jiang <gerry@linux.alibaba.com>

src/lib.rs

@@ -113,6 +113,7 @@ mod common;
 mod connection;
 mod request;
 mod response;
+mod router;
 mod server;
 
 pub use self::common::headers::{Headers, MediaType};
@@ -120,4 +121,5 @@ pub use self::common::{Body, Method, Version};
 pub use self::connection::{ConnectionError, HttpConnection};
 pub use self::request::{Request, RequestError};
 pub use self::response::{Response, StatusCode};
+pub use self::router::{EndpointHandler, HttpRoutes, RouteError, TryClone};
 pub use self::server::{HttpServer, ServerError, ServerRequest, ServerResponse};