Don't normalize keys for paths and shim options.

[seggen-ibuildings]

JavaScript modules may have dashes ("-") in their names. Symfony automatically normalizes array keys unless you specifically tell it not to. (http://symfony.com/doc/current/components/config/definition.html#normalization)

This improvement prevents normalization of paths and shim keys.

[ihortymoshenko]

@seggen-ibuildings, please create a topic branch.