Improve navigation

[snim2]

In previous years we had a few more links in the nav bar of the site. This year we have fewer (and adding more tends to split the nav bar onto two lines). However, there are some really important pages that readers will have to dig pretty hard to find. This includes the research and teachers pages, the diversity statement, the speaker mentor page; and when the DjangoGirls and Trans*Code pages are added they will also be hard to find.

We need to think a bit more about the nav bar and the home page to bring some of these pages to the foreground. At the moment we risk teachers, DjangoGirls people, etc. looking briefly at the site and leaving.

That said, I'm not sure I have any concrete solutions, except perhaps making the nav bar font a little smaller :(