Update Swagger UI to 3.x

[frol]

The changes are quite radical, so it will take some time to get things going.

Just for the reference: noirbizarre/flask-restplus#267

[frol]

While the upstream has already updated Swagger-UI to 3.x, I don't really like the new design... It is a pity, but it is hard to read it, especially, when you "try it out", the response is hard to identify on the page :(

[frol]

Also,

• broken OAuth2 support
• The JSON Form Editor is not implemented