Recognize abbreviations with period

Would be great to be able to extract abbreviations that have a period. 

For example, we currently have this:

```
>>> extract("Num. 1:2 and 1 John 1")
[('I John', 1, 1, 1, 10)]
```

would be nice to have 

```
>>> extract("Num. 1:2 and 1 John 1")
[('Numbers', 1, 2, 1, 2), ('I John', 1, 1, 1, 10)]
```
