Amends rotation intervals
Remove comments; amend rotation interval

The comments in this file are already well documented; they serve little purpose
in-line in the file, and add extra overhead if the commands are ever changed.

The rotation interval has been changed to weekly; we keep a year's worth (52
weeks) of logs before logrotate rotates them. This was done for security
purposes.
Merge branch 'add-clam' of github.com:alphagov/govuk_offsitebackups-puppet into add-clam