config.action_controller.perform_caching isn't used anymore in assets pipeline, instead we are using config.assets.digest now

AssetNotPrecompiledError should be raise when config.assets.digest = false, config.assets.compile = false and manifest file isn't present

not add more.!

Assets pipeline: fix in manifest location and remove unused code

Also:

- Refactor AssetDebuggingTest.
- Use the %r regexp syntax. That way we don't need to escape the /'s.

Add config.allow_debugging option to determine if the debug_assets query param can be passed by user

Rails 3.1 throws a Errno::ENOTDIR if files are put in assets directories

Otherwise, if bad data is cached in tmp/clear then the next invocation
of assets:precompile (or a regular incoming request) will pickup files from
tmp without regenerating them from source.

Otherwise, if bad data is cached in tmp/clear then the next invocation
of assets:precompile (or a regular incoming request) will pickup files from
tmp without regenerating them from source.

Rails 3.1 throws a Errno::ENOTDIR if files are put in assets directories

This is useful for engines with own application.{js|css}-files.
See: https://github.com/rails/rails/issues/1520

This group is required by default only on development and test
(you can change it on config/application.rb).

`rake assets:precompile` will automatically add the assets group
to Rails.groups (and consequently Bundler.require) and should work
transparently.