get_dataframe() mishandles index and date type

[timcoote]

the dataframe returned by get_dataframe () is quite odd from a pandas point of view and doesn't appear to agree with the api documentation.

Shouldn't the 'date' column be of type pandas.Timestamp, rather than ?
Should time run forwards?
Should the 'date' column be the index of the returned dataframe?

[timcoote]

I see that there's a (failing) PR to address this issue (#20)