networkx version incompatibility

[jasper1918]

The latest networkx2.1rc1 version renames several functions.

Specifically:

    adj_mat = nx.to_pandas_dataframe(node_graph)
AttributeError: 'module' object has no attribute 'to_pandas_dataframe'

The function is now called to_pandas_adjacency per: https://github.com/networkx/networkx/pull/2811

Either specify a version in the install or handle dynamically in the script.