Adds the collapsed mixin to the styling for .nav-sidebar
ensuring the nav-sidebar is collapsed on load via media
queries. Removes the need for an intermediate class to
collapse the sidebar on mobile viewports
Updated toggleCollapsedSidebar to check for desktop breakpoint
Adds rspec view tests that expect the nav sidebar
to have a class that will cause the nav sidebar
to be rendered collapsed with or without js.
Tests the nav sidebar on the admin, group,
instance statistics, user profile and project
sidebars.
