This can be done using the class attribute cache_timestamp_format

Conflicts:
	railties/guides/source/configuring.textile

There's no reason for guides to reference old behaviors. They should
be current as of the versions of Rails that they ship with, and including
older information just clutters thing.

I discussed this change with @fxn and he agrees.

We have three or four different introduction sentences to the guides.
After this commit, we use the same one everywhere.

Talked with @fxn about this. Bullet points should have periods at the ends.

They was extracted from a plugin.

See https://github.com/rails/rails-observers

[Rafael Mendonça França + Steve Klabnik]

Also remove references for RAILS_ASSET_ID from the guides

[ci skip]

Removed the asset_path configuration from the guides and added an entry
in the upgrading_ruby_on_rails guide

[ci skip]

This reverts commit f5b9ed4f.

REASON: Translation work can not be done in the docrails repository

This option is now unsupported in sprockets-rails.

Date.beginning_of_week thread local and beginning_of_week application config option added (default is Monday)

erb tag wasn't closed well

The new option allows any Ruby namespace to be registered and set
up for eager load. We are effectively exposing the structure existing
in Rails since v3.0 for all developers in order to make their applications
thread-safe and CoW friendly.

The flag was mainly used to add a Rack::Lock middleware to
the stack, but the only scenario the lock is desired is in
development.

If you are deploying on a not-threaded server, the Rack::Lock
does not provide any benefit since you don't have concurrent
accesses. On the other hand, if you are on a threaded server,
you don't want the lock, since it defeats the purpose of using
a threaded server.

If there is someone out there, running on a thread server
and does want a lock, it can be added to your environment
as easy as: `use Rack::Lock`

With a value of "nosniff", this prevents Internet Explorer from MIME-sniffing a response away from the declared content-type.