Support for asset-url in rails 4

[jescalan]

Fairly important feature for me -- I would love to take a stab at this, but my understanding of the internals here is definitely limited. Is this a feature anyone has thought about or has any tips or pushes in the right direction for?

[lucasmazza]

@Jenius what is missing to support Rails 4? Feel free to take a stab on it if you want, or even finish off the code on #58.

[jescalan]

I'm not sure, but it doesn't work at all with the hashing. It's good in development, but once the assets are hashed it just ignores the hashes entirely.