add knackered settings objects

this is the basic code to load configuration settings for knackered.

### Example Usage
```ini
[db]
host=127.0.0.1
port=3306
name=knackered

[api]
access_key=some_key
```

```python
from knackered.settings import Settings

config = Settings("config.ini")
config.db.host
config.db.port
config.db.name
config.api.acccess_key
```