webpack: Allow importing nav.css automatically when using the react component
webpack: Allow importing nav.css automatically when using the react component

Initially this was removed so that we allow scss overrides of the global
variables, but since we don't use the original mobile version of this
component it's not needed any more to filter out this component's css from
'null-loader'.

garrett/cockpit,mvollmer/cockpit,garrett/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,deryni/cockpit,garrett/cockpit,cockpit-project/cockpit,mvollmer/cockpit,deryni/cockpit,deryni/cockpit,deryni/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,garrett/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,martinpitt/cockpit,deryni/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,garrett/cockpit,martinpitt/cockpit,deryni/cockpit,mvollmer/cockpit