Moved httpd library from ewsgi/connectors/standalone/lib/httpd to httpd.

Reused the http_network library as well inside httpd library.

library/server/httpd/httpd_server_observer.e

@@ -0,0 +1,27 @@
+note
+	description: "Summary description for {HTTPD_SERVER_OBSERVER}."
+	date: "$Date$"
+	revision: "$Revision$"
+
+deferred class
+	HTTPD_SERVER_OBSERVER
+
+feature -- Event
+
+	on_launched (a_port: INTEGER)
+			-- Associated server launched listening on port `a_port'.
+		deferred
+		end
+
+	on_stopped
+			-- Associated server stopped.
+			--| the server may restart itself after being rescued.
+		deferred
+		end
+
+	on_terminated
+			-- Associated server terminated.
+		deferred
+		end
+
+end