Support a more complex sass library

[flyingmachine]

This change was motivated by my need to support a Bower installation of the Susy sass library.

Changes:

• Usig jsass 5.2.0 instead of 3.3.1. The API changed quite a bit. One nice thing about 5.2.0 is that Import objects have a .getAbsoluteUri method that returns an Import's directory
• I removed the following from core.clj:

(find-resource (io/resource (add-underscore url)))      
(find-resource (io/resource url))

It looks like these were used to support the use case in the test file where we were creating a file in a temporary directory, and trying to import resource files from the created file. I couldn't see why one might want this functionality.

Still, that's not enough reason to remove the functionality. The larger reason is that those lines were causing the susy import to throw the exception An import loop has been found.

[Deraen]

Thanks!

I'l try to remember why those lines existed and if removing those has some other consequences.

Other thing, I don't want 4000 lines of external code added to the repo. Either:

• Import Susy from WebJars: [org.webjars.bower/susy "2.2.12"] and @import "susy/sass/susy"; or
• Write small local test case

[Deraen]

I updated Jsass in another commit: https://github.com/Deraen/sass4clj/commit/41ac016018174c3c2848bc694da44f8ee4bfe0b4