Replace CoffeeScript logo with official version

I went hunting for the official CoffeeScript logo, it’d been lost for a while but @jashkenas provided it once again: jashkenas/coffeescript#3627

It’s now been eternally saved by being included in the CoffeeScript repo, as mentioned in #3.

I converted the `eps` file provided, made it the ‘standard’ resolution used in this repo and cleaned the file. Some of what I've done is based on what I think should be done, and discussed in [#2], particularly with regards to the use of `<g>`.

This logo has two logical groups (the cup and the words), plus the ‘whole group’. I'm undecided on whether including a global `<g>` is useful. Maybe global properties should just be placed on the `<svg>` element.

Also, the layout changed from the cup being on top of the words, to being inline with the words.

Resolves #3.

[#2]: https://github.com/chloi/preprocessor-logos/pull/2#issuecomment-65608347