Switch from CSSselect and CSSwhat to css-select and css-what

[tripu]

Get rid of these two npm warnings:

$ npm install
npm WARN deprecated CSSselect@0.4.1: the module is now available as 'css-select'
npm WARN deprecated CSSwhat@0.4.7: the module is now available as 'css-what'
[…]

The problem is that whacko is stuck with CSSselect ~0.4.0, which in turn is tied to CSSwhat.

There have been no commits to whacko in the last three months. We should explore submitting a PR to fix this, fork whacko, or switch to its parent project, cheerio.

[tripu]

Fixed in #278.