Allow configuration to tell cat-log to fetch logs from (local) disk rather than remote host

[jarich]

For jobs running via PBS, job logs are not available until the job has completed (yes, even if the job runs for 4 hours and generates GBs of logs). I don't know why this is the case, but it is the case. PBS spools log messages somewhere and then moves them into the correct locations when the job is done. As such, if remote log fetching is enabled, then pulling the job logs from the job host means additional SSH connections, network traffic and load on the login hosts for zero value. This is even more the case when those connections are left open by users who navigate to another tab or whatever.

It would be ideal if there was a configuration item that told cat-log to only serve files from local disk, if that is what the user wanted.