autosave_association issue that occurs when table has unique index

fixes bug introduced by  #3329
These are the conditions necessary to reproduce the bug:
- For an association, autosave => true.
- An association record is being destroyed
- A new association record is being created.
- There is a unique index one of the association's fields.
- The record being created has the same value as the record being
destroyed on the indexed field.

Before, the deletion of records was postponed until after all
insertions/saves.  Therefore the new record with the identical value in
the indexed field caused a non-unique value error to be thrown at the database
level.

With this fix, the deletions happen first, before the insertions/saves.
Therefore the record with the duplicate value is gone from the database
before the new record is created, thereby avoiding the non-uniuqe value
error.

Postgresql array columns don't properly escape single quote strings when loading fixtures

Support transactions in Migrator.run

Conflicts:
	activerecord/CHANGELOG.md

Fix freeze applying to cloned objects

Reorganize MessageEncryptor

1) According to OpenSSL's documentation, cipher.random_iv must be called
   after cipher.encrypt and already sets the generated IV on the cipher.

2) OpenSSL::CipherError was moved to OpenSSL::Cipher::CipherError in
   Ruby 1.8.7. Since Rails 4 requires at least Ruby 1.9.3, support for
   the old location can be dropped.

 - A string in an array of strings that has a quote char (') needs to have that quote char escaped if the array is getting wrapped in quote chars.

Otherwise we get extra indent for the <td> elements due to the extra
spaces at the beginning of the lines, like this:

      <tr>
          <td><%= author.name %></td>
          <td><%= link_to 'Show', author %></td>
        <td><%= link_to 'Edit', edit_author_path(author) %></td>

This reverts commit 521035af, reversing
changes made to 222011db.

Reason: This broke the tests

This reverts commit 57583879.

Conflicts:
	railties/lib/rails/generators/app_base.rb

Reason: sprockets 2.9.1 fixes this issue

DB with postgres string array column doesn't load fixtures well

Add support for extracting the port from the :host option and for
removing the subdomain by using nil, false or ''.

Adding a boolean route constraint checks for presence/absence of request property

Avoid leak into controller's action_methods

Fix subject-verb agreement in error msg (and other grammar stuff)

Use secure source for rubygems in engine tests

Refactoring increment and decrement in local cache

same, so their logic is being refactored.

Refactored the storage of a temporary version of the local cache.

its own method.

associations

add :nodoc: mark to *Registry classes [ci skip]

[ci skip]