Added the current score to the appbar in scoresheet.html

[poelstra]

Don't think using <h3> is the best option to do this, because it's semantically not a header but 'just' a piece of info. So probably a <span class="score"> or something is better.

However, I don't think it's a big issue, so:

• it would be nice if you can change it
• otherwise, just let me know, and I'll merge it as-is

[alanggreen]

@ThinkRedstone I think @poelstra 's point about H3 is valid