Support :multiple option on input tags that also have :index

When you have an explicit index set, then when you build an input tag
with :multiple => true, it doesn't add [] to the end of its name, although
it should.

This comment is not valid since that `if` is there to make possible to
do:

    remove_index :users, :name

Instead of:

    remove_index :users, column: :name

What is a valid use case.

[ci skip]

This was there due historical reasons since
7dc45818 to give the user the
possibility to create unique indexes passing "UNIQUE" as the third
argument

Closes #8104

Fixed grammar in migration pending error.

Conflicts:
	actionpack/lib/action_controller/metal/mime_responds.rb
	activerecord/lib/active_record/attribute_methods.rb
	guides/source/working_with_javascript_in_rails.md

This reverts commit 3b890520.

Reason: changes made to a test, albeit in commented lines - non-uniform
change.

[ci skip]

This reverts commit cd17ee55.

Reason: Let's note that this is discouraged, not remove the docs

[ci skip]

This reverts commit f4ad0ebe, reversing
changes made to 8b2cbb3a.

Conflicts:
	actionpack/CHANGELOG.md

REASON: This added introduced a bug when you have a shorthand route
inside a nested namespace.

See
https://github.com/rafaelfranca/rails/commit/281367eb770faf8077c1fd6194188e92ed1637a1

Fixed mapping of Solomon Islands.

Fixes #8095.

For reference, here is the discussion about the mapping being
incorrect:
http://rubyforge.org/pipermail/tzinfo-users/2012-November/000114.html

memoize calculated ip without additional variable

There is no need in additional `@calculated_ip` instance variable.

When calling first(n) or last(n) in a collection, Active Record was
improperly trying to set the inverse of instance in case that option
existed. This change was introduced by
fdf4eae5.

In such cases we don't need to do that "manually", since the way
collection will be loaded will already handle that, so we just skip
setting the inverse association when any argument is given to
first(n)/last(n).

The test included ensures that these scenarios will have the inverse of
instance set properly.

Fixes #8087, Closes #8094.

Squashed cherry-pick from d37d40b2 and c368b660.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/lib/active_record/associations/collection_association.rb

Fix #8086 (BestStandardsSupport rewrites app X-UA-Compatible header)

Now `BestStandardsSupport` middleware appends it's `X-UA-Compatible` value to app's value.
Also test for `BestStandardsSupport` middleware added.

Closes #8091

Small change to remove warning unused variable.

Make sure that RAILS_ENV is set when accessing Rails.env

Fixes #8025

This reverts commit f1765019.

This reverts commit a8560fa3.

Fix find_in_batches against string IDs when start option is not specified

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.