rgw: create a separate logrotate file for radosgw

Fixes: #3813
Since radosgw package is separate from the ceph package,
it also needs to have a separate logrotate. The default
path for radosgw log is changed to /var/log/radosgw,
and it now has a different logrotate script.
Updating both deb and rpm packaging.

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>