Logging now goes to files, not to databases

[robcarver17]

You will want to include the following in your private config:

log_directory: '/home/rob/logs'

Otherwise the logs will go to whatever pst considers the current directory to be.

Existing log information will remain in databases, but will be gradually autodeleted and in a month will be entirely gone.

I've also removed the methods in interactive_diagnostics that allow you to view logs.