Coerce strings in create_join_table.

If you accidentally pass a string and a symbol, this breaks. So
we coerce them both to strings.

Fixes #7715

Fixed a typo

Postgresql adapter: fix handling of BC timestamps

Refactoring, testing and documenting pg_connection.distinct

fix guide with field_with_error proc example

Initialize accessors to remove some warnings in Ruby 2.0

Postgresql doesn't accepts limits on text columns

Improved Error handling when parsing database.yaml, Fixes #8143

Provides a better error message incase the database.yaml
has some errors.

Fix error when using a non-hash query argument named "params" in `url_for`.

Before:

    url_for(params: "") # => undefined method `reject!' for "":String

After:

    url_for(params: "") # => http://www.example.com?params=`

Closes #8233

Merge url for tests and add changelog entry for #8233.

With a "params" argument, the following error is raised:

    undefined method `reject!` for "":String

render every partial with a new `PartialRenderer`.

This resolves issues when rendering nested partials.
Previously the `PartialRenderer` was reused which led to
situations where the state of the renderer was reset.

Closes #8197

Explicit multipart messages respect :parts_order

As issue #7978, the order in which ActionMailer
sends multipart messages could be unintentionally
overwritten if a block is passed to the mail
method. This changes the mail method such that
:parts_order is always respected, regardless of
whether a block is passed to mail.

require bundler groups to include rake-tasks in engines

Displaying error message if validation fail in examples (p tag was missing)

Remove not used variable.
Remove config attr_reader causing warning.
Fix indent in runner file.

When using sqlite3 it was attempting to find the database file based on
Rails.root, the problem is that Rails.root is not always present because
we try to first manually load "config/database.yml" instead of loading
the entire app, to make "rails db" faster.

This means that when we're in the root path of the app, calling "rails db"
won't allow us to use Rails.root, making the command fail for sqlite3
with the error:

    ./rails/commands/dbconsole.rb:62:in `start':
      undefined method `root' for Rails:Module (NoMethodError)

The fix is to simply not pass any dir string to File.expand_path, which
will make it use the current directory of the process as base, or the
root path of the app, which is what we want.

When we are in any other subdirectory, calling "rails db" should work
just fine, because "config/database.yml" won't be found, thus "rails db"
will fallback to loading the app, making Rails.root available.

Closes #8257.

AR::Base.becomes should not change the STI type

Conflicts:
	activerecord/CHANGELOG.md

Add rename_index to change_table.

Properly deprecate #pending from AS::TestCase. This has been previously
removed from master, and is now back with a deprecation instead, to avoid
people having tests breaking when upgrading an app.

Please check #4575 for more background.

Check https://github.com/rails/rails/pull/4575#issuecomment-5765575.