Add handles, round avatars, spacing, interactivity

I made a few changes to the default layout:

avatars are now round
there's more spacing between avatars
we also show the github handles / usernames

You can get back to the more compact layout by clicking the checkbox.

Additionally, the grid now updates when you type in the text box, so you don't need to edit JS & HTML. A nice side effect of this is that it should work with GitHub Pages now. Just rename the HTML file to index.html, turn on GitHub Pages, and it should be good to go?

jhutchings1 / thank-you-builder

Add handles, round avatars, spacing, interactivity #1