Not all dependecies are listed

[dpryan79]

Would it be possible to add pandas (and numpy) to the list of dependencies? They're both imported in various places but not listed. This occasionally causes problems for packages importing plotly, since pip may not install all dependencies.

Xref: deeptools/deepTools#669

[dpryan79]

More specifically, one can't import plotly.figure_factory without pandas in newer versions, due to it being used by plotly/figure_factory/_county_choropleth.py.