title: Resetting dask dataframe index to allow join
body: <p>Given <a href="http://dask.readthedocs.io/en/latest/dataframe-api.html#dask.dataframe.DataFrame.reset_index" rel="nofollow">http://dask.readthedocs.io/en/latest/dataframe-api.html#dask.dataframe.DataFrame.reset_index</a> says dask doesn't support <code>drop=True</code> for <code>reset_index()</code> how do I join 2 dataframes together with different index (as viewed by <code>head()</code>) </p>