Add tutorial: setting-up Bluetooth - PulseAudio

Probably needs more work, but this is a good stage to ask for comments.
On Windows the `tutorials` page did not look OK:
![tutorial_on_win7](https://cloud.githubusercontent.com/assets/8142081/5077594/11e1ed2a-6ea5-11e4-9b5d-810e3c4345cd.png)

But that could well be a jekyll on win artefact.

Please use liquid template for images. Also, brickman screenshots should be given meaningful names and go in `images/brickman` in this repo.

Example:

    {% include screenshot.html source="/images/brickman/main-menu-bluetooth-selected.png" scale="50" %}