Fix bug with pasting that can result in unwrapped text nodes

https://next.getflow.com/workspaces/1/tasks/5603855

The task is about blockquotes not working but the reason for it not working is due to a pasting bug... sometimes text is pasted in the wysiwyg div and isn't wrapped in any tags, so the main wysiwyg div is replaced with a blockquote instead of the wrapping tag.  

This checks when you paste html to make sure that every node is wrapped in an element before it's appended to the wysiwyg div.