Move headers from server/include to include/maxscale

- Headers now to be included as <maxscale/xyz.h>
- First step, no cleanup of headers has been made. Only moving
  from one place to another + necessary modifications.

server/modules/include/rwsplit_internal.h

@@ -25,7 +25,7 @@
 extern "C" {
 #endif
 
-#include <query_classifier.h>
+#include <maxscale/query_classifier.h>
     
 /* This needs to be removed along with dependency on it - see the 
  * rwsplit_tmp_table_multi functions