Installed Bootstrap; spiffy application template
Root route; removed index.html; refined CSS styling
More natural routes for static pages
Navbar into partial; layout helper; fix routes; refactor rspec tests
 - Moved the navbar into a partial, _header.html.erb.
 - Applied class 'active' to navbar links using a new helper, active_if_current,
   to highlight the current page.
 - corrections to routes.
 - refactored Rspec tests to be half as long, using let, subject, and before.
Basic Users resource; Sign In dropdown widget
 - generated a Users resource, with just a #new stub action / view for now.
 - added a beautiful dropdown widget for a Sign In login form.