Update Menu

[jlbooker]

Update the menu module to optimize its database queries and use caching.

┆Issue is synchronized with this Asana task

[jlbooker]

This change should including implementing the concept of Monocline Grouping. That is, only allow one level deep nesting of menu items.

For reference:

• A chapter from Cooper's About Face 3 on Avoiding Hierarchies
• An essay from Information Architects on how this concept is applied in OS X.

[jlbooker]

Additionally, the entire menu should be generated on each page load and sent to the client. Then, use Javascript to show/hide sections of the menu. This will greatly simplify the server-side menu generation. The entire menu can be cached, and only regenerated when modified (link is added, moved, etc). This also allows for proper REST model to be used to manipulate the menu.