Remove stream write validation to avoid incorrect validation failures

[jonmmease]

Fix for #1108

Removed validation since stream writes don't actually have the same validation rules as traces.

cc @gnthibault

[jonmmease]

@Kully , I'm going to go ahead and merge this so it's on master for testing over the next few days. Please still take a glance if you have a chance over the next couple of days.

[Kully]

@jonmmease fantastic! It's working now.

One note is that setting x and y to an array doesn't append any data to the figure but instead updates the chart to the most recent x=[...], y=[...] you are writing to it. But setting x=5, y=2 now appends to the figure and updates the chart just fine.

So yeah, removing the validation seems to be bypassing the issues we were having before. Are you now trying to write a validation for streaming that isn't broken?

[jonmmease]

The behavior of appending with a scalar and overwriting with a list is consistent with the pre 3.0 behavior. That's really handled by plot.ly not plotly.py.

I don't have any particular plans for adding validation back, or for the streaming API in general. But if someone else is interested in improving this side if things that would be fine with me.