Align configuration protocol with common practices

[mobileink]

The current config protocol relies on the .coda-config directory being in the home directory of the user running the daemon. But common practice is to run a daemon under a dedicated UID/GID (e.g. _coda/_coda) with no shell or home directory.

Suggestion:

• put config files in /etc, e.g. /etc/coda.d/daemon.json
• logs to /var/log/coda
• tmp files to /tmp or /var/tmp

and in general to follow the FSH

Related: #6013

[jadechip]

+1 I'm having all kinds of issues trying to run the deamon in a production k8 cluster. The above would be a good solution.