Refactor db:structure:dump task.

Remove extra test case.

Make the test description better reflect what is happening

Rename testcase name. It's wrong in the context.

Rename MySQLTestPurge to MySQLPurgeTest for consistency.

Refactor db:charset task

In a similar vein to Pat's work on create, drop etc, the db:charset
task is now a one liner in databases.rake

Added test for case when view doesn't have logger method when using 
ActionController::Metal controller.

Ensure that cache-control headers are merged

Added test for case when view doesn't have logger method when using ActionController::Metal controller.

Closes #6675

This happens when A has_many many B and A accepts_nested_attributes B that has a numeric colum
with initial 0 value. So a.update_attributes({:b_attributes => { :id => b.id, :numeric => 'foo' }})
passes the validation test but, the value of :numeric doesn't change.
his commit forces that the update fails with the above conditions.

Fixes #6393
Fixes #2331

Added `stored_attributes` hash which contains the attributes stored using
ActiveRecord::Store. This allows you to retrieve the list of attributes
you've defined.

    class User < ActiveRecord::Base
      store :settings, accessors: [:color, :homepage]
    end

    User.stored_attributes[:settings] # [:color, :homepage]

This allows you to retrieve the list of attributes you've defined.
Usable for e.g. selects in the view, or interators based on the
attributes you wish to store in the serialized column.

The problem:
Accessing a HashWithIndifferentAccess does not return the the same object
that is stored in the hash (i.e. equal?) causing unexpected results:

    hash = HashWithIndifferentAccess.new {|h, k| h[k] = []}
    hash[:a] << 1  # => [1]
    hash[:a]       # => [], expected [1]

The cause:
When a block is provided to generate default values the generated values
are duped if they are arrays. The duped value is stored in the hash but
the original value is returned when the hash is accessed.

The fix:
The duping is there for allowing frozen arrays containing hashes to be
modified. The fix restricts the duping to this case. Note that if default
function generates a frozen array an error will be raised on assignment
before and after the patch.

Closes #3811

make events not use date and time to determine parent_of. fixes #5932

There are several aspects to this commit, that don't well fit into broken down
commits, so they are detailed here:

 * When a user uses response.headers['Cache-Control'] = some_value, then the
   documented convention in ConditionalGet is not adhered to, in this case,
   response.cache_control is ignored due to `return if
   self[CACHE_CONTROL].present?`
 * When a middleware sets cache-control headers that would clobber, they're
   converted to symbols directly, without underscores. This would lead to bugs.
 * Items that would live in :extras if set through expires_in, are placed
   directly in the @cache_control hash, and not respected in many cases
   (somewhat adhering to the aforementioned documentation).
 * Although quite useless, any directive named 'extras' would be ignored.

The general convention applied is that expires_* take precedence, but no longer
overwrite everything and expires_* are ALWAYS applied, even if the header is
set.

I am still unhappy about the contents of this commit, and the code in general.
Ideally it should be refactored to no longer use :extras. I'd likely recommend
expanding @cache_control into a class, and giving it the power to handle the
merge in a more efficient fashion. Such a commit would be a larger change that
could have additional semantic changes for other libraries unless they utilize
expires_in in very standard ways.

Removing composed_of

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

 ORA-02289: sequence does not exist for `SELECT "BLACK_JOKES_SEQ".NEXTVAL FROM dual`