Careers teaser in comment and error console. Bug 937719.

This adds a teaser to both the top of the page and the error console encouraging people who look at these kinds of things to head over to careers.mo and join us.

I would like feedback on a few things:
1) wording
2) implementation (I used a macro so I can reuse the same string and js_escape it; the same thing does not appear possible with a straight import)
3) repeating the console.log after 10 seconds, under the assumption that it'll probably get buried when slower connections keep loading assets. Am I overthinking this?