Apply active class only to parents of #spine child navigation

Our wildcard search for `*=active` could target other navigation
list items outside of `#spine`. We should avoid stomping on things
like that.
Add documentation to the current and active wildcard search

Fixes #131
s/navagation/navigation/
Merge pull request #160 from washingtonstateuniversity/ui-spine-nav-active

[PR] Update "current" and "active" documentation in Spine navigation