Allow unicode dictionaries. 

When using dictionary files that are UTF8-encoded the generator raises an Error. I basically just had to change one line in the code. Now I can use the generator with a dictionary file containing i.e. arabic or russian words like this:

```python
path = '/path/to/my/arabic-utf8.dic'
dictionary = codecs.open(path, "r", "utf-8").readlines()
g = Generator(dictionary=dictionary)
```