changed default logrotate config; using weekly and maxsize 10M. #23

Using weekly and 10M so that couchdb log available on /_log for example
will contain more data than one day's worth. It's generally more
conventient to have more than one day's worth of logs in a file. This
should also guarantee a maximal rentention period of 21 weeks.  But not
a minimal retention since you don't know when you will hit the 10M cap
that triggers a rotate.