dax: logging: Change timestamp format

Previously the timestamp in the logs was seconds.microseconds, while
this is useful for the timestamps in the database, it would perhaps be
nicer to have a more human readable timestamp in the logs.

Thus we now use the following:

    [YYYY-MM-DD HH:MM:SS tz-offset]

e.g

    [2013-07-04 00:06:38 +0100]

Signed-off-by: Andrew Clayton <andrew@dnsandmx.com>
dax: access log: Simplify the access.log message

Just make the log message less wordy.

Signed-off-by: Andrew Clayton <andrew@dnsandmx.com>