Create Pluto logo, styling, etc.

[ChimeraCoder]

The Pluto project should have its own logo (or, for now at the very least, a separate styling/theme/etc.) to distinguish itself from Planet-hackNY (which we've been using as the styling until now).

This also goes along well with @exchgr's idea of making Pluto easily theme-able (which shouldn't be hard, since we're basing this on Foundation from the start).

I'm partial to bluish (or maybe purplish) for Pluto (I like this artist's rendering of the surface) but I'm persuadable.