Related to bug #217, added command 'fail accept <errno>' to debug client's commands.

Reproduce #217 by connecting with telnet to debug client interface and execute command:

fail accept 23

and try to execute read query, for example, with

mysql -h 127.0.0.1 -P 4008 -u maxuser -pmaxpwd -e 'select current_user(), @@server_id'

server/core/gateway.c

@@ -216,6 +216,8 @@ memset(dcb_fake_write_errno, 0, sizeof(unsigned char)*1024);
 memset(dcb_fake_write_ev, 0, sizeof(__int32_t)*1024);
 fail_next_backend_fd = false;
 fail_next_client_fd = false;
+fail_next_accept = false;
+fail_accept_errno = 0;
 #endif
         l = atexit(skygw_logmanager_exit);