Add support for more file types in media gallery

[bstocks]

Currently only image types are supported in the media gallery. It would be useful to be able to include videos as well.

[bstocks]

The following docs will need to be updated when this is complete:

https://github.com/ongoworks/reaction/blob/master/docs/products.md
https://github.com/ongoworks/reaction/blob/master/docs/features.md

[jamesdeantv]

Any update on this feature request?

[aaronjudd]

@kieckhafer @mikemurray we should review this while looking at new/alternate approaches for replacing CFS. I'm closing for now, because this will be revisited when we replace CFS and update the image gallery.

[zrisher]

FYI for those landing here from the docs, here is the new tracking issue - #1221