[cas-dev] Logging in CAS4

[Marvin S. Addison]

In general logging should have a high signal to noise ratio.  I think
logging statements _before_ a critical action and _not_ after it are
helpful to achieving that goal.  Saying nothing is equivalent to
success, while a stack trace or WARN message indicates failure.  If
there is a feeling that before/after logging is necessary, I would like
the following logging statements at a lower level (e.g. TRACE) so they
can be disabled.

Some things in particular I'd like to see/keep:
 - WARN messages for authentication failures that contain an identifier
from the credential (username, X.509 subject DN)
 - INFO messages for authentication success that contain the resolved
CAS principal
 - INFO messages for ticket generation, consumption, and expiration
 - Service URLs in ST generation messages

The current logging standands are good and could only be improved by
fewer, more concise messages.

Regards,
Marvin