BUG: 0.12.0 using DataFrame.to_hdf() with mode='a' does not append the data
`to_hdf(....., append=True,table=True)` raising, should accept this

Is there a way to use DataFrame.to_hdf() so that data can be appened the data? Somehow to_hdf(filename, table_name, mode='a', table=True) overwrites the data while to_hdf(filename, table_name, table=True, append=True) gives the following error:

> Traceback (most recent call last):
>   File "M:/Projects/PortfolioAnalytics/Code/Python/attribution/TopContributors.py", line 1035, in <module>
>     portfolio_data.to_hdf(filename, OUTPUT_NAME_PORTFOLIO, table=True, append=Settings.TC_OUTPUT_APPEND)
>   File "C:\Python27\lib\site-packages\pandas\core\generic.py", line 521, in to_hdf
>     return pytables.to_hdf(path_or_buf, key, self, *_kwargs)
>   File "C:\Python27\lib\site-packages\pandas\io\pytables.py", line 194, in to_hdf
>     f(store)
>   File "C:\Python27\lib\site-packages\pandas\io\pytables.py", line 188, in <lambda>
>     f = lambda store: store.append(key, value, *_kwargs)
>   File "C:\Python27\lib\site-packages\pandas\io\pytables.py", line 658, in append
>     self._write_to_group(key, value, table=True, append=True, **kwargs)
> TypeError: _write_to_group() got multiple values for keyword argument 'table'
