fix(nav): fix React warning with onExpand prop

[priley86]

What:
fix React warning introduced in #1490

Warning: Unknown event handler property `onExpand`. It will be ignored.
    in li (created by NavToggle)
    in NavToggle
    in NavExpandable (created by NavSection)
    in NavSection (created by Connect(NavSection))
    in Connect(NavSection) (created by Navigation)
    in ul (created by NavList)
    in NavList (created by Navigation)
    in nav (created by Nav)
    in Nav (created by Navigation)
    in div (created by PageSidebar)
    in PageSidebar (created by Navigation)
    in Navigation (created by App)
    in div (created by Page)
    in Page (created by App)
    in App (created by Route)
    in Route
    in Router
    in Provider

Additional issues:

[redallen]

CircleCI doesn't matter, you have my approval to merge.