Make bench a little bit more configurable

Кажется, в текущем видем можно все схлопнуть до такого:
```js
var PATH = require('path'),
    FS = require('fs');

function minimizer(minMethod) {
    return function(inputFile, outputFile) {
        var css = FS.readFileSync(inputFile, 'utf-8'),
            res = {};

        start = Date.now();
        min = minMethod(css);
        end = Date.now();
        res.time = end - start;

        FS.writeFileSync(outputFile, min);
        res.size = FS.statSync(outputFile).size;

        return res;
    };
}

module.exports = {
    minimizers: {
        CSSO: minimizer(require('csso').justDoIt),
        cleancss: minimizer(require('clean-css')().minify),
        cssshrink: minimizer(require('cssshrink').shrink),
    }
    paths: {
        toRawCSS: PATH.join('css', 'raw'),
        toMinCSS: PATH.join('css', 'min')
    }
};
```