Fix Strong Parameters docs [ci skip]

It's only possible to inherit from ActiveRecord::Base and not include
it.

unshift html-scanner into $LOAD_PATH rather than append

Unused variable warning removed

empty rails gem's require_paths

This file was using mime_types before load the Mime::Type class.
When trying to register first Mime::Type it load mime_type that loads
mime_types in the end.

Requiring mime_type ensure that we have the class definition and the
mime types

We are already in the AR namespace, there's no way for it to be
undefined. See the cousin commit 13e72db7

Refactor a bit teardown fixtures to avoid two conditionals.

Accept symbols as #send_data :disposition value

Length validation handles correctly nil. Fix #7180

Conflicts:
	activemodel/CHANGELOG.md

@steveklabnik can't spell 'distance.'

Add changelog for #7997.

This was forgotten when we did the merge.

Corrects typo in test name [ci skip]

Log output from activemodel's railtie_test directly to STDOUT.

There's no logging going on here, but since we initialize the app, the
logger is set and the folder is automatically created. With this change,
the default logger is not created, so there is no logging folder anymore.

Conflicts:
	activemodel/test/cases/railtie_test.rb

after this patch, running the tests in activemodel will no longer
create an untracked log/ folder inside of activemodel

Don't run explain on slow queries for database adapters that don't support it

make sure that individual parts `ActiveModel` can be required by itself

When nil or empty string are not allowed, they are not valid.

Move the routes for each test inside the test method so that
it's easier to see which routes are applicable to which test.

To ensure that each test wasn't invalidated the changes were
done by first removing all of the routes, ensuring that all
of the tests failed and then adding the routes back to each
test one by one. One test for `assert_recognizes` was
removed as it wasn't actually testing the defined routes and
is now tested more thoroughly in routing_assertions_test.rb.

One downside is that the test suite takes about 1s longer
due to having to using `method_missing` for handling the url
helpers as using `include url_helpers` isn't isolated
for each test.

Use Class.new with a block instead of tap to configure it.

assert_template: validating option keys

It only handles the keys locals, partial, layout and count.

    assert_template(foo: "bar") # raises ArgumentError
    assert_template(leiaute: "test") # raises ArgumentError

Add explicit opt-out for fragment cache digesting

This add support for sending an explicit opt-out of the "Russian-doll"
cache digest feature on a case-by-case basis. This is useful when cache-
expiration needs to be performed manually and it would be otherwise
difficult to know the exact name of a digested cache key.

More information: https://github.com/rails/cache_digests/pull/16

assert_template("") will now fail no matter whether a template has been rendered or not.

Don't call will_change! for datetime nil->"".

Setting a nil datetime attribute to a blank string should not cause the
attribute to be dirty.

Fix #8310

Document :hidden_field_id option for fields_for [ci skip]