feat(server): accept combined certificate files

Openssl::with_cert_and_key is often useless in its current form: in most
setups, one need to provide the intermediate certificate chain to
Openssl. One way would be to change with_cert_and_key to allow passing a
third file containing the authority chain. Fortunately, thers is
another option: Openssl accepts combined certificates (your certs, then
whatever certs you need to link it to the widely distributed ones). This
is not exotic, both nginx and apache use this setup.

src/net.rs

@@ -710,7 +710,7 @@ mod openssl {
         where C: AsRef<Path>, K: AsRef<Path> {
             let mut ctx = try!(SslContext::new(SslMethod::Sslv23));
             try!(ctx.set_cipher_list("DEFAULT"));
-            try!(ctx.set_certificate_file(cert.as_ref(), X509FileType::PEM));
+            try!(ctx.set_certificate_chain_file(cert.as_ref(), X509FileType::PEM));
             try!(ctx.set_private_key_file(key.as_ref(), X509FileType::PEM));
             ctx.set_verify(SSL_VERIFY_NONE, None);
             Ok(Openssl { context: Arc::new(ctx) })