Remove non-json from health message. (paritytech#332)

Author: tomusdrw

http/src/response.rs

@@ -42,7 +42,7 @@ impl Response {
 		Response {
 			code: StatusCode::SERVICE_UNAVAILABLE,
 			content_type: HeaderValue::from_static("application/json; charset=utf-8"),
-			content: format!("Service Unavailable: {}", msg.into()),
+			content: format!("{}", msg.into()),
 		}
 	}
 

http/src/tests.rs

@@ -179,7 +179,7 @@ fn should_handle_health_endpoint_failure() {
 
 	// then
 	assert_eq!(response.status, "HTTP/1.1 503 Service Unavailable".to_owned());
-	assert_eq!(response.body, "Service Unavailable: {\"code\":-34,\"message\":\"Server error\"}\n");
+	assert_eq!(response.body, "{\"code\":-34,\"message\":\"Server error\"}\n");
 }
 
 #[test]