WIP on HAS theme: content and styles for nav bar

[#53913087] This gets the needed content in to the nav bar, hides it from the MW/default themes, and makes a first cut at formatting it for HAS.

https://www.pivotaltracker.com/story/show/53913087
Moves activity_nav partial from page to shared
rm old comment
Remove Lato for Helvetica in HAS themes
Shows the whole HAS/NGS nav menu for [#53913087].

There are some missing details, but the raw navigation menu is in place now.

https://www.pivotaltracker.com/story/show/53913087