Beta: Story 435: Left nav grouping

Separate left nav into two menus
Old HTML tested with new CSS without problems
Start convention of using _ prefix on temporary template data since
zero team will need some indication of what is stable and what is not

Change-Id: I45666d6a66c1b487dec157fce3ef30f8db93bfc5
Merge "Beta: Story 435: Left nav grouping"