Rename to .cc, fix Makefile bugs, add example_clock

sse.cc

@@ -0,0 +1,8 @@
+#include "sse.h"
+
+SSEServer::SSEServer(int port, const std::function<void(std::unique_ptr<SSEStream>)>& callback)
+		: fastcgi_server_(port, [](std::unique_ptr<FastCGIRequest> request) {}) {}
+
+void SSEServer::Serve() {
+	fastcgi_server_.Serve();
+}