Delete 'Others' section from hits

* Others confused all users in research
* The list cannot be acted on or resolved from within transition alone
* Attempts to create mappings for these statuses will put the system in
a confusing state (eg. for robots.txt)
* Remove references to Other from all tests, models, controllers and
views
Merge pull request #101 from alphagov/others-begone

Delete 'Others' section from hits