add has_expanded_navbar

...t/migrations/0308_districthomepage_has_expanded_navbar.py

.../migrations/0065_electionshomepage_has_expanded_navbar.py

main/blocks.py

main/migrations/0146_mainhomepage_has_expanded_navbar.py

main/migrations/0147_alter_mainhomepage_content.py

shared/models/main.py

...plates/styleguide2/includes/molecules/menus/carousel.html

...mplates/styleguide2/includes/organisms/layout/navbar.html

uniweb/migrations/0117_uniwebhomepage_has_expanded_navbar.py