Adds a normalizePath method to tree.evalEnv.prototype with which to normalize paths, i.e. , remove /../ or /./ segments stuck in the middle.
Unit tests have been updated to reflect these changes.
Although IE8 does support data-uris, it only does so with a limit of 32KB. It's a silly limitation, but a source of potential bugs. When the limit is exceeded, the data-uri() function will simply return a normal url() value with a relative path to the asset.
One may pass --no-ie-compat to lessc to avoid this safeguard.
