Don't strip out trailing slashes when filtering

* Fix #68376922
* Or more specifically, put trailing slashes back after canonicalising

An example of the original problem:
“When trying to filter path on /sta/, it filters on /sta. As a result,
"/statistics" ends up included in my "/sta/" mappings list, when all I
want is /sta/ things for the Standards and Testing Agency”
Add tests for existing hits ignore behaviour
Ignore more generic site furniture URLs
Merge pull request #258 from alphagov/improve_furniture_asset_ignoring

Improve furniture asset ignoring
Put transition date on analytics graph

* Show a line on the analytics graph on the date at which the site
mappings went live
* Only show a line when site is live and the graph spans the date of
transition
Merge pull request #260 from alphagov/transition-date-on-graph

Put transition date on analytics graph
Tidy up bulk add success messages

* When all are updated, don’t mention “0 created”
* When both updating and creating, don’t show a broken tagged message
(“All .”)
* When tagging, conditionally append “All “ to the start of the
tagged_with string
* When only “1 mapping updated”, remove the full stop as the message is
effectively a title.
Merge pull request #261 from alphagov/fix-broken-modal-title

Tidy up bulk add success messages
Simplify shared error messages template

Just display the error if there is only one, rather than iterating
over the array anyway.
Merge pull request #264 from alphagov/simplify_error_message_template

Simplify shared error messages template
Fix host validations

Rails makes it far too easy to think we're doing validation right
when we're not:

- `validates` is used with ActiveRecord's pre-defined validation
  helpers, such as presence: true
- `validate` is used to call custom validation methods defined on a model

If we use `validate` with a pre-defined helper, it doesn't raise an
error but doesn't do the validation; we had this problem for all our
validations on the Host model.

This also adds a :with_its_aka_host trait to the host factory to
make it easier to create a host and the corresponding aka host together.
Validate that a non-aka host has no canonical_host_id
Merge pull request #265 from alphagov/validate_real_host_not_aka_of_another

Fix Host validations
Inform users of entire site redirects or archives

- This is to avoid users getting confused by a site having zero
  mappings, or trying to add mappings for globally redirected or
  archived sites.
- There are two new sites database table columns of type boolean -
  `global_archive` and `global_redirect`. False = not
  redirected/archived and True = redirected/archived.
Redirect the mappings pages to the site dashboard

- This is only for sites which are globally redirected or archived,
  so users cannot edit those site's mappings.
Use the existing `global_http_status` database column

- Remove the migration that added `global_archive` and
  `global_redirect` columns to the sites table, following a comment
  from @jennyd.
- Exclude `MappingsController#find_global` from the before_filter of
  `MappingsController#check_global_redirect_or_archive`, otherwise
  it fails on not finding `@site`.
Remove the italics around the redirected or archived hostname

- Following feedback from @fofr.
If a global HTTP status exists, don't show the Action column on hits
Add tests for the page redirection if there's a global archive/redirect
Make a Cucumber feature pass when `.action` doesn't exist in the table