Fix for import relative path for url with parameters

We generate final less file by script on server with parameters like `blah1/blah2/blah_pack.script?use=/less/src` in generated final less file we import `./variables.less` with relative path.
In older version of less.js it's works fine. But in 2.0.0 it's broken.

less.js tries to load variables.less by url `blah1/blah2/blah_pack.script?use=/less/variables.less` but it's wrong