Implement support for instant data propagation with Redis

sponge/src/main/resources/luckperms.conf

@@ -114,6 +114,20 @@ data {
   sync-minutes=3
 }
 
+# Settings for Redis.
+#
+# If enabled and configured, LuckPerms will use the Redis PubSub system to inform other
+# connected servers of changes. Use the command "/luckperms networksync" to push changes.
+# Data is NOT stored on redis. It is only used as a messaging platform.
+#
+# If you decide to enable this feature, you should set "sync-minutes" to -1, as there is no need for LuckPerms
+# to poll the database for changes.
+redis {
+  enabled=false
+  address="localhost:6379"
+  password=""
+}
+