Better Context Scaffolding

A number of incremental improvements to bootstrap integration in the
project.

- Replace static resources with dynamic (less-based) resources so
we can customize bootstrap later

- Update Context model with ActiveModel::Naming so that generated pages
display model correctly.

- Add bootstrap theming to Context CRUD pages. Will probably replace or
remove these later but they look nicer

- Route the root to /contexts so the starter page doesn't display