Set API Keys as Hash at initilize

I want set api key as Hash not as File at initialize, like

```
Bazil::Client.new(api_key: ('myapikey', 'mysecretkey'))
```

or

```
Bazil::Client.new(api_key: {api_key: 'myapikey', secret_key: 'mysecretkey'})
```

or another clever way.
