big update: hooks and plugins

plugins/example/example_plugin.c

@@ -0,0 +1,18 @@
+#include "../../uwsgi.h"
+
+void uwsgi_init(struct uwsgi_server *uwsgi){
+	fprintf(stderr,"i am the example plugin initialization function\n");
+}
+
+int uwsgi_request(struct uwsgi_server *uwsgi, struct wsgi_request *wsgi_req, char *buffer) {
+	char *http = "HTTP/1.1 200 Ok\r\nContent-type: text/html\r\n\r\n<h1>Hello World</h1>" ;
+	wsgi_req->response_size += write(uwsgi->poll.fd, http, strlen(http));
+
+	return 0;
+}
+
+
+int uwsgi_after_request(struct uwsgi_server *uwsgi, struct wsgi_request *wsgi_req, char *buffer) {
+	fprintf(stderr,"i am the example plugin after request function\n");
+	return 0;
+}