caches_action extension (with :if and :layout keys)

I just sent a patch to Lighthouse that extends caches_action
functionality.

A couple of changes were made to ActionController::Caching::Actions:

  * Added conditional option (:if) to caches_action method (just like
in caches_page)

  * Added :layout flag to caches_action method. If you specify :layout
=> false, the layout will not be cached, only the action content. This
is useful since most application has user info in the layout. If
the :layout is not set (nil) or set to true, we have the default
behavior.

  * Changes were documented

  * Tests were added

  * Test bug fix: added sleep(0.01) to assure that Time.now will be
different.

[],
José Valim.

ps: I'm just sending this e-mail cause Lighthouse says so. Apologies
if I am off-topic. =)

Ops, the patch is here:

http://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/166

But You would have guessed. =P

[],
José Valim.