logging level conventions

[Vernon Mauery]

When making a change in netipmid, the conversation came up about user 
errors versus system errors. There are times that both should be logged, 
but obviously system errors are more severe. So in that project, I made 
system errors (like failure to communicate on dbus, etc.,) as log<ERR>() 
and user errors (like bad credentials) as log<INFO>().

Does anyone else think that the project as a whole should make this 
distinction between system errors and user errors? Maybe add something 
to the coding style?

--Vernon