[#23] Requests to retreive an objects karma should always end with a "?"

This makes sure that any request to retrieve the karma of an object ends with a  question mark.

`karma joe?` will work, `karma joe` will not.

Resolves #23.
What about removing a level of indentation by using a single regex?

```js
/^karma\s+(.*)\?$/i
```

Perhaps this isn't the "proper" way of doing things with lubot, for performance reasons or something. @justafish?