Permenant Key/Value Storage

I recently implemented KVStore feature to Warlock. This is a simple kv database that opperated in-memory and so everything is lost if the server crashes and/or restarts.

Now that I have a fairly robust B-Tree class available, I'd like to make it an option to store these values to the disk. This will be off by default for performance, but can be turned on.

The only issue here is going to be handling the automatic expiry that has been implemented.