Addbetterdemo

[msfeldstein]

I added another demo sketch that might be useful to people making brushes without an HMD. It has different size/color strokes and is visible from the default view. Since it's json people can modify it to use their brush instead. If this isn't something we want in the repo i can host it elsewhere.

I wrote up some notes about it here: https://medium.com/@msfeldstein/make-a-vr-paintbrush-in-a-painter-68f802716cf9#.j8zcujazp