Fixed bug with cutoff and allowFuture

To reproduce the bug use these settings: 
```js
    $.timeago.settings.cutoff = 7 * 86400000;// one week in milliseconds
    $.timeago.settings.allowFuture = true
```
You will se that the cutoff have no effect on a future date.
Merge pull request #183 from Nyholm/patch-1

Fixed bug with cutoff and allowFuture