Merge pull request #12463 from ulyssecarion/master

Call `rails plugin new yaffle` in the plugins guide. [ci skip]
Merge pull request #12473 from claudiob/document-after-touch

Add documentation for after_touch [ci skip]
Merge pull request #12283 from JuanitoFatas/rails-on-rack

[ci skip] Add explanation on Rack::Sendfile middleware in rails_on_rack.md.
Respect `SCRIPT_NAME` when using `redirect` with a relative path

Example:
    # application routes.rb
    mount BlogEngine => '/blog'

    # engine routes.rb
    get '/admin' => redirect('admin/dashboard')

This now redirects to the path `/blog/admin/dashboard`, whereas before it
would've generated an invalid url because there would be no slash between
the host name and the path. It also allows redirects to work where the
application is deployed to a subdirectory of a website.

Fixes #7977
(cherry picked from commit 9dbd208562ccd3d68009a72d37cbfe29b94f98c4)

Conflicts:
	actionpack/CHANGELOG.md
Use bcrypt's public cost attr, not internal constant

See:

- https://github.com/codahale/bcrypt-ruby/pull/63
- https://github.com/codahale/bcrypt-ruby/pull/64
- https://github.com/codahale/bcrypt-ruby/pull/65
Merge pull request #12494 from tjschuck/bcrypt_cost_attr

Use bcrypt's public cost attr, not internal constant