Ensure - servers/roots - file is accessible.

Updated initialisation routine `init2' to report an error when
the global root server list - servers/roots - is not accessible
to the resolver. Without the root server list `dnscache' won't
be able to function properly.
Improve resolver logs a little.

Changed - log.c - routines a little to improve dnscache resolvers'
log structure for better comprehension. Added timestamps.
Replaced hexadecimal values with human readable decimals.
Added few indentations and acronyms - cc: cached, Q: query,
R: response, rr: resource record, ss: stats.