Tests: Add helpers

1. Tests are divided into 2 folders: `core` and `options`.
    `core` is supposed to collect tests for `cli.js` and `csscomb.js`.

2. Add file `test/mocha.js` and run mocha programmatically.
    This allows adding helpers for all tests.
    Since `bdd` is default ui and `dot` is default reporter, remove options.

3. Add test helpers: `readFile()`, `shouldBeEqual()` and `shouldDetect()`.

4. **Skip failing tests.**

Good news is [we have helpers](https://github.com/csscomb/csscomb.js/blob/1ee621541f48cfdc26e8b1e2947457dd07a99799/test/mocha.js) that can be used in all tests.
Code is simpler and I believe it will be easier to add cases for #89.

The fun part is **2 tests are broken now and skipped**: [one](https://github.com/csscomb/csscomb.js/blob/1ee621541f48cfdc26e8b1e2947457dd07a99799/test/options/quotes.js#L4) + [two](https://github.com/csscomb/csscomb.js/blob/1ee621541f48cfdc26e8b1e2947457dd07a99799/test/options/integral.js#L14).
Since those cases appear to fail in `dev` branch as well when tested manually in console, I assume they have never worked in fact.
So I've commented them out and created issues.

![tumblr_mmt4ofu00z1soylsvo1_500](https://f.cloud.github.com/assets/872004/1812739/56902348-6e8c-11e3-94e7-9efbba5d608a.gif)