OS X: update transparency settings for Yosemite

The old setting doesn't work:

https://github.com/mathiasbynens/dotfiles/commit/8692d489d5949977be03bfce0b54bf335b8f4167

The new setting does:

https://github.com/mathiasbynens/dotfiles/commit/44169a963aeeeb846b31fdf47ccceefd851663c5

I'm not sure I'll keep this permanently, as the transparency does look
pretty nice; but I want to try it out for at least a few days and see
what I think.
OS X: switch to Graphite appearance

Again, not sure if I'll run with this, but at least at night, the much
less garish appearance under Graphite is preferable.