Added DEFAULT_TIMEOUT and RESULT_TTL in settings.RQ_QUEUES

As stated in #57 supports code:

```python
RQ_QUEUES = {
    'default': {
        'HOST': 'localhost',
        'PORT': 6379,
        'DB': 0,
        'PASSWORD': 'some-password',
        'DEFAULT_TIMEOUT': 60,
        'RESULT_TTL': 30,
    },
    'high': {
        'URL': os.getenv('REDISTOGO_URL', 'redis://localhost:6379'), # If you're on Heroku
        'DB': 0,
    },
}
```

You can close #57 and try to think of tests...
Sorry, but I disagree with this change. "default" is just a queue name and need not be enforced. If no "RESULT_TTL" is specified for a queue, it should just fallback to RQ's default values.