Initial commit of YoUltraDNS client implementation.

It's not Demands-based so far, but this is my working version of UltraDNS client, which I use for Domainservice refactoring.
I realize it's not perfect, and comments are very appreciated. I don't promise do fix them quickly, because this ticket is urgent, and it's important to complete this work till 1th Sept, but I plan to refactor it later if required.

Usage:
=====

```
from youltradns import UltraDNSClient
client = UltraDNSClient(settings.NEUSTAR_USERNAME, settings.NEUSTAR_PASSWORD)
client.create_zone('myzone.com')
```
I think there was misunderstanding in our internal discussions.  It's my very personal opinion, but I would like to see `UltraDNSClient` as something what now called `UltraDNSRestAPI` (because in fact its a client) and optionally we might need `UltraDNS` model if there is any behaviour we want to put on our `youltrandsns` side.