if format is unknown NullMimeTypeObject is returned

If a unknown format is passed in a request, the methods html?, xml?, json? ...etc
Nil Exception.

This patch add a class NullMimeTypeObject, that is returned when  request.format is unknown
and it responds false to the methods that ends with '?'.

It refers to #7837, not fixes because it's not considered a improvement not a bug.

Fix `attributes_before_type_cast` for serialized attributes.

Public method `attributes_before_type_cast` used to return internal AR structure (ActiveRecord::AttributeMethods::Serialization::Attribute), patch fixes this. Now behaves like `read_attribute_before_type_cast` and returns unserialised values.

Fix #6951. Use query cache/uncache, when using not only database.yml but also DATABASE_URL.

This reverts commit 7e0cf563.

Conflicts:
	actionmailer/CHANGELOG.md

See discussion at
https://github.com/rails/rails/commit/7e0cf563639bc7508da381b1b8321c7a89be1aa8#commitcomment-2075489

This reverts commit 7b290ad1.
debugger gem is now working ok with p286

Allow include_root_in_json to be inheritable by using the class_attribute created by Active Model serialization module.

Make callstack attribute optional in AS:Deprecation

This can occur if the user is using :integer columns to store boolean
values. Now we are handling the boolean values but it still raises if
the value can't type cast to integer and is not a boolean. See #7509.

Fixes #8067.

Conflicts:
	activerecord/CHANGELOG.md

Add test for code change introduced in this commit f20032fa

Provide a call stack for deprecation warnings where needed.

It's sometimes hard to quickly find where deprecated call was performed, especially in case of migrating between Rails versions. So this is an attempt to improve the call stack part of the warning message by providing caller explicitly.

Should not eager_load app/assets
Conflicts:
	railties/CHANGELOG.md

Atomic.rb assumes it may chown/chmod a file but doesn't handle the EPERM error.

Previously this code just assumed it is capable of changing the file
ownership, both user and group. This will fail in a lot of scenario's
unless:
* The process is run as a superuser (root);
* The owning user and group are already set to the user and group we're
  trying to chown to;
* The user chown'ing only changes the group to another group it is a
  member of.
If either of those conditions are not met the filesystem will simply
deny the operation throwing an error.

It is also not always possible to do a chmod, there might be a SELinux
policy or another limitation preventing the user to change the file
mode. To this end the chmod call has also been added to the rescue
block.

I've also added a little comment above the chmod command that doing a
chmod on a file which has an ACL set will cause the ACL to be
recalculated / modified.

Checking for the constant doesn't work

SQLite3Adapter#type_cast should not mutate arguments

Added ActiveRecord::Relation#none! method

Unbreak update_column/update_columns for the primary key attribute.

Didn't work before because it updated the model-in-memory first, so the DB query couldn't find the record.

Replace flow-control exception with explicit test.

Do not render views when mail() isn't called. (NullMail refactoring)

Removing JSON for other ruby

create_table raises an ArgumentError when the primary key is redefined.