Some refactoring for phpunit.
Added a hook reset to fix a bug when processing files with different options.
Simplified the version string reported by the command line utility.
Making `csscrush_string()` return a true string instead of Stream object (with a __toString method).
Fixed `Url::getAbsolutePath()` not using the current process doc_root.
Added parsing for `git describe --long` output, and method to get this information if available.
Added tests dev dependencies to composer.json.