Change Server to contain a Vec of (ip, port) pairs to allow repeat listening

Expose Server::many for creating a Server that will listen on many (ip, port)
pairs.

Handler still receives a simple Iterator of (Request, Response) pairs.

This is a breaking change since it changes the representation of Listener,
but Handler and Server::http are unchanged in their API.

Fixes #7

Cargo.toml

@@ -13,6 +13,12 @@ git = "https://github.com/seanmonstar/mime.rs"
 [dependencies.unsafe-any]
 git = "https://github.com/reem/rust-unsafe-any"
 
+[dependencies.intertwine]
+git = "https://github.com/reem/rust-intertwine"
+
+[dependencies.move-acceptor]
+git = "https://github.com/reem/rust-move-acceptor"
+
 [dev-dependencies.curl]
 git = "https://github.com/carllerche/curl-rust"