fix(gen:app:navbar): improve navbar component when using ui-router

Changes:
- Use `ui-sref` instead of `href` or `ng-href` when ui-router is chosen
- Use `ui-sref-active` instead of `ng-class='{active: isActive()}'` when ui-router is chosen
- Use `$scope.menu[n].state` instead of `$scope.menu[n].link` when ui-router is chosen (attempt to remove possible confusion)
- Omit `$scope.isActive` when ui-router is chosen
- Simplify `navbar(jade).jade` templating (remove extra `<% if (filters.auth) %>` tag)

closes #436