Remove old feedback system

The feedback system wasn't used and was starting to cause problems on
Debian 9 where the libcurl required different version of OpenSSL than what
MaxScale was linked against.

server/core/maxscale/modules.h

@@ -14,21 +14,6 @@
 
 /**
  * @file modules.h  Utilities for loading modules
- *
- * The module interface used within the gateway
- *
- * @verbatim
- * Revision History
- *
- * Date     Who                 Description
- * 13/06/13 Mark Riddoch        Initial implementation
- * 08/07/13 Mark Riddoch        Addition of monitor modules
- * 29/05/14 Mark Riddoch        Addition of filter modules
- * 01/10/14 Mark Riddoch        Addition of call to unload all modules on shutdown
- * 19/02/15 Mark Riddoch        Addition of moduleGetList
- * 26/02/15 Massimiliano Pinto  Addition of module_feedback_send
- *
- * @endverbatim
  */
 
 #include <maxscale/cdefs.h>
@@ -107,20 +92,6 @@ void dprintAllModules(DCB *);
  */
 RESULTSET *moduleGetList();
 
-/**
- * @brief Send loaded modules info to notification service
- *
- *  @param data The configuration details of notification service
- */
-void module_feedback_send(void*);
-
-/**
- * @brief Show feedback report
- *
- * Prints the feedback report to a DCB
- */
-void moduleShowFeedbackReport(DCB *dcb);
-
 typedef struct mxs_module_iterator
 {
     const char* type;