excludefiles: Exclude various common log files when building the appliance.

These log files can get pretty big, and that causes problems
like this one:

http://linuxforum.ru/viewtopic.php?id=35381

and this one:

https://bugzilla.redhat.com/show_bug.cgi?id=1099172

In both cases the problem was /var/log/lastlog which is apparently a
large sparse file.  Supermin cannot cope with sparseness, so it copies
the whole file non-sparse.  But since this could affect other log
files this commit covers various common log file names and patterns.

Thanks: semperN