particularly, `all(options)` would warn

This reverts commit 14fc8b34.

Reason: we need to discuss a better path from this removal.

Conflicts:
	activerecord/lib/active_record/reflection.rb
	activerecord/test/cases/base_test.rb
	activerecord/test/models/developer.rb

This feature adds a lot of complication to ActiveRecord for dubious
value. Let's talk about what it does currently:

class Customer < ActiveRecord::Base
  composed_of :balance, :class_name => "Money", :mapping => %w(balance amount)
end

Instead, you can do something like this:

    def balance
      @balance ||= Money.new(value, currency)
    end

    def balance=(balance)
      self[:value] = balance.value
      self[:currency] = balance.currency
      @balance = balance
    end

Since that's fairly easy code to write, and doesn't need anything
extra from the framework, if you use composed_of today, you'll
have to add accessors/mutators like that.

Closes #1436
Closes #2084
Closes #3807

This reverts commit fa6d921e.

Reason: Not a fan of such massive changes. We usually close such changes
if made to Rails master as a pull request. Following the same principle
here and reverting.

[ci skip]

Only constantize class_name once.

For future reference, this is the regex I used: ^\s*#\s*\n(?!\s*#). Replace
with the first match, and voilà! Note that the regex matches a little bit too
much, so you probably want to `git add -i .` and go through every single diff
to check if it actually should be changed.

This makes it possible to filter invalid input values before they are passed
into the value-object (like empty strings). This behaviour is only relevant
if the :allow_nil options is set to true. Otherwise you will get
the resulting NoMethodError.

Fixed typo in composed_of example with Money#<=>, was comparing amount itself instead of other_money.amount

- persisted? is the API defined in ActiveModel
- makes it easier for extension libraries to conform to ActiveModel APIs
  without concern for whether the extended object is specifically
  ActiveRecord

[#5927 state:committed]
Signed-off-by: NSantiago Pastorino <santiago@wyeworks.com>

Signed-off-by: Nwycats <wycats@gmail.com>

Break up DependencyModule's dual function of providing a "depend_on" DSL and "included" block DSL into separate modules. But, unify both approaches under AS::Concern.

Signed-off-by: NMichael Koziarski <michael@koziarski.com>
[#892 state:committed]