Add support for openbracketformat

[rogueyoshi]

https://github.com/openbracketformat/openbracketformat

There is an ongoing effort for this schema to be adopted by most of the major tournament bracket sites (start.gg, challonge, etc.) and I think it would be a great addition not only for this but for bracket-manager as well. It covers a lot of modern needs, especially for esports games.

(this issue was created as suggested in Drarig29/brackets-viewer.js#99)