* Add proper check_slot() calls to all of the user input that is going into
  the DB (already had taint checking), since batchexp is now available for
  interactive use from ops.

* Remove separate DB insertions of noswap/noidleswap reasons from web
  script, and pass on the command line from web to batchexp. Now inserted
  in the backend script so that they can be provided on the command line
  when batchexp is used interactively.

* Change defaults in backend script; experiments now default to swappable
  and idleswap; previously defaulted to not swappable and no idleswap.

* Remove [-s] (swappable) and add [-S <reason>] option. -S sets experiment to
  not swappable, with supplied reason (text string).

* Add [-L <reason>] option. -L sets experiment to no idleswap, with
  supplied reason (text string).

* Add several missing table_regex entries for experiments table.