Add show version command to maxadmin

After upgrades, it is usually useful to see which version of MaxScale is
running. By adding a command, we can see the actual version of the running
daemon process instead of the version of the current binary.

server/modules/routing/debugcli/debugcmd.c

@@ -46,7 +46,7 @@
  *
  * @endverbatim
  */
-#include <my_config.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -74,7 +74,7 @@
 #include <maxscale/listmanager.h>
 #include <maxscale/maxscale.h>
 #include <maxscale/config_runtime.h>
-
+#include <maxscale/version.h>
 #include <maxscale/log_manager.h>
 #include <sys/syslog.h>
 
@@ -113,6 +113,11 @@ struct subcommand
 static void telnetdShowUsers(DCB *);
 static void show_log_throttling(DCB *);
 
+static void showVersion(DCB *dcb)
+{
+    dcb_printf(dcb, "%s\n", MAXSCALE_VERSION);
+}
+
 /**
  * The subcommands of the show command
  */
@@ -283,6 +288,12 @@ struct subcommand showoptions[] =
         "Show all maxadmin enabled Linux accounts and created maxadmin users",
         {0, 0, 0}
     },
+    {
+        "version", 0, 0, showVersion,
+        "Show MaxScale version",
+        "Show the MaxScale version number",
+        {0, 0, 0}
+    },
     { EMPTY_OPTION}
 };