Use a named pipe for logging in upstart example

[sorentwo]

The ability to log directly to /dev/kmsg was removed in Ubuntu 14.04, making the existing example config fail to perform any real logging. Appending a pipe to the last exec within the script block gives upstart an incorrect PID to work with, which can lead to various issues.

This uses a FIFO solution that logs to syslog at any permission level and doesn't leave anything on the file system afterwards.

[mperham]

I'd suggest an alternative: punt on the problem, log to stdout and have the output go to /var/log/upstart/<servicename>.log. wdyt?

[sorentwo]

I was under the impression that sidekiq 3.0+ was favoring user jobs, which have the caveat that they can't log to /var/log/upstart/<servicename>log. From the cookbook:

User jobs cannot currently take advantage of job logging. If a user job does specify console log, it is considered to have specified console none. Logging of user jobs is planned for the next release of Upstart.

I'm fine with punting on the default config entirely. I only suggest that:

1. Remove the exec &> /dev/kmsg as it fails in recent Ubuntu's
2. Keep some documentation about how to actually achieve system logging with a user job via the fifo/logger trick. There may be a place for that in the wiki, but I haven't dug into it.

[mperham]

I definitely don't recommend user jobs (e.g. /home/bob/.upstart) for normal users. Where did you get that idea? Sidekiq isn't typically used in a shared Linux system but rather run as a system service on a machine dedicated to running a business app (e.g. a Rails app).

Sounds great.

[sorentwo]

I was referencing #1532, which referenced User Jobs. Anyhow, I'll modify the PR to simply remove logging and note the default log path.

[sorentwo]

@mperham: Pushed that change. Purely documentation and synching the two examples now.