Add a slot align-strategy prop

[weotch]

• vertical-align - The default
• absolute - The transform apporach
• table - Does display:table and display:table-cell on slot, useful when you want to use a min-height height on the visual.

[weotch]

I updated the above, min-height on tables doesn't work in Firefox.

Also, if .vv-visual is set to a table, the overflow:hidden doesn't apply to the .vv-video in Firefox. The overflow should be moved inside, perhaps to the transition that wraps the video. That kinda makes sense since the overflow is only REQUIRED for the video.

[weotch]

Don't remember why this was necessary ... I don't think it will be now.