Provide initialize_on_precompile which, when set to false, does not initialize the app for precompilation. Defaults to true.

Avoid use of existing precompiled assets during rake assets:precompile run

To the app developer, this means configuration add in
config/initializers/* will not be executed.

Plugins developers need to special case their initializers that are
meant to be run in the assets group by adding :group => :assets.

Conflicts:

	railties/CHANGELOG
	railties/test/application/assets_test.rb

Revert "Provide a way to access to assets without using the digest, useful for static files and emails"

This reverts commit 82afaa06.

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