Add configurable proxy command logging.

This commit adds a config switch that allows users to turn off
 the logging of proxy commands. It is set to off by default to
 prevent unwanted log spam and keep current behaviour.
Log proxy commands

This commit changes the PluginManager to print a message to
console and the log when a proxy command is executed.
This may assist with debugging and miscellaneous
investigations.

proxy/src/main/java/net/md_5/bungee/conf/Configuration.java

@@ -47,6 +47,10 @@ public class Configuration implements ProxyConfig
      * Should we check minecraft.net auth.
      */
     private boolean onlineMode = true;
+    /**
+     * Whether we log proxy commands to the proxy log
+     */
+    private boolean logCommands;
     private int playerLimit = -1;
     private Collection<String> disabledCommands;
     private int throttle = 4000;
@@ -75,6 +79,7 @@ public class Configuration implements ProxyConfig
         timeout = adapter.getInt( "timeout", timeout );
         uuid = adapter.getString( "stats", uuid );
         onlineMode = adapter.getBoolean( "online_mode", onlineMode );
+        logCommands = adapter.getBoolean( "log_commands", logCommands );
         playerLimit = adapter.getInt( "player_limit", playerLimit );
         throttle = adapter.getInt( "connection_throttle", throttle );
         ipForward = adapter.getBoolean( "ip_forward", ipForward );