DataFrame.to_html encoding
see also [mailing list](https://groups.google.com/forum/?fromgroups#!topic/pystatsmodels/e5J1yvCGmmI)

``` python
In [34]: df = pandas.DataFrame({'A': [u'\u03c3']})

In [35]: df
Out[35]:
   A
0  σ

In [36]: print df.to_html()
---------------------------------------------------------------------------
UnicodeEncodeError                        Traceback (most recent call last)
...
UnicodeEncodeError: 'ascii' codec can't encode character u'\u03c3' in position 1: ordinal not in range(128)

In [37]:  
```

further more from the thread:

```
... I wanted to spot as well that
force_unicode is in the doc but is not available.
TypeError: to_html() got an unexpected keyword argument 'force_unicode'
```
