Start fixing errors found after migration

district/models.py

district/templates/district/base.html

shared/blocks.py

shared/models.py

shared/static/shared/img/newsletter.svg

shared/static/shared/js/vue-formulate-helper.js

...tic/shared/vendor/vue-formulate-2.5.3/js/formulate.min.js

...shared/vendor/vue-formulate-2.5.3/js/formulate.umd.min.js

...emplates/shared/blocks/newsletter_subscription_block.html

uniweb/models.py

uniweb/templates/uniweb/base.html