Refresh a lot of the copy

This includes some small and some larger(er) changes, which I'll call out specifically in a moment, but generally:

* Typos and wording (small)
* Bring some tech stuff up to date (small)
* Change a few things about the rails engineering job description (bigger)
I don't think anyone's side projects or open source work are big factors in our process and there's so many great people out there that either can't or don't have time to publicize their work in the open.  So, changed this to focus in on what I think we were really going for with "passion" which is respect for the craft of software engineering.  There are a ton of ways to demonstrate that other than open-source projects, so hopefully this feels more inclusive.