from_networkx fails with networkx 2.0

Hi - When using networkx 2.0 (nx) loading a graph from nx results in a ValueError. ValueError: expected an element of ColumnData(String, Seq(Any)), got {'index': NodeView((0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33))}

This is because nx 2.0 wraps graph.nodes in a View. And therefore, from_networkx code needs to be changed from:

nodes = graph.nodes()
edges = graph.edges()

to:

nodes = dict(graph.nodes())
edges = dict(graph.edges())

Lastly pip nx is version 2.x on conda it is 1.x. Most people are on 1,x

[bryevdv]

@stonebig the fix is more involved we are still investigating

[bryevdv]

@gryBox we typically try to have PRs and issues separate, you can just put issues: closes #6971 at the top of the PR