Merge pull request plotly#674 from plotly/update-changelog

Update changelog.

Merge pull request plotly#658 from plotly/2.0.0

2.0.0

Merge pull request plotly#656 from plotly/frames-support

Improve `frames` support in graph_objs.py.

Merge pull request #201 from plotly/update-image-endpoint

Move from genimage —> v2/images/

Merge pull request #196 from plotly/delete_fullData

dont return fullData on widget events

Merge pull request #192 from plotly/plot_postmessage

`plot` method in `GraphWidget`

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