I2PControl: make it possible to access logs via the json-rpc interface
This makes it so that JSON-RPC applications can ask for the log output. Also requires an addition to the JSON-RPC spec before it can be merged, and I need to bring it up with orignal on Monday. Right now the format is very simple, it takes one or zero parameters. Either, it is the filter for the log, or if the parameter is empty, the most recent log messages.