Cpsk datematch

* Plugin is now able to also match date when user specifies it in query. For instance `10.12.2014 bus z TO do BA`
* Also added more examples
* Don't throw exception when there are no results, rather return "Nothing found"

This closes #29 
Could you please put logic expressions into parents here? It would make this much more readable, like

```python
("zajtra" in msg or "pozajtra" in msg) and date is None
```