Add ability to capture debug solution logs

Adds a gen_event server to capture logs. The approach is to write a fixed number of logs of each type: ok, error, timeout, unreachable. Files are named by count (1, 2, 3, ...) and when the max count is reached, the counter resets. So if you set to 200, you'll only ever have 200 files under each category of log.

Not enabled by default, but can be enabled/disabled by connecting to a node and adding/removing the handler. Directory and max files also configurable at handler add time.