Make config reload more lightweight

[Kristian Larsson]

The current config reload is a real heavyweight. It runs in a polling mode where every second we re-read the entire config. The last loaded config is stored away as a string and we compare the newly read config with this one. If there's a difference we load the new config.

I see two potential improvements:

• look at mtime of file to determine if there's a chance it's been modified since we last read it
• use something like inotify to let the kernel notify us of chances to the file instead of polling