Bug 1038395 - Build CTA landing page for learners / makers

<http://localhost:9006/from/firefox-2014/>
<http://localhost:9006/for/learners/>
<http://localhost:9006/for/mentors/>
Ah that's cool! Is that documented anywhere in the code? Seems like it might be nice to make it a named constant like `ANONYMOUS_CONTRIBUTOR_EMAIL`, and then at the definition of that constant, put a comment in that says what you just wrote, so that a curious reader could grep for the def'n and eventually find it, but that's just a suggestion (and perhaps something that's better filed as a separate bug rather than added on to this PR).