Add option to disable built-in log management

[bernardd]

This change adds the option to specify 'none' for log_dir config value. The effect is to disable the build-in log management in ChicagoBoss, allowing your to use in your own error_logger based logging system instead.

This is helpful for incorporating a CB app into a larger system where there is already an existing logging framework (handling log rotation etc) based on error_logger.

[evanmiller]

I wonder if "no logging" should be the default, and specifying a log_dir enables it. Or maybe have a separate log_enable option. Anyway I support the idea but I think that log_dir shouldn't be overloaded with 'none'. What do you think?

[bernardd]

I don't really have a strong opinion. I went the way I did to avoid changing the default behaviour and to avoid adding a whole new config item for such a relatively trivial change, but if you think it's better done a different way I certainly won't object :)

[evanmiller]

Let's go with "log_enable" that defaults to true. I generally like to optimize for the person looking for a specific bit of functionality, rather than overload options. And of course, the size of the change should have nothing to do with whether there should be a "whole new config item" :)

Anyway, if you send me an update I will get it merged in.

[bernardd]

Changed as requested.

[evanmiller]

Thanks!