Create submittable version of newletter form

district/models.py

district/templates/district/base.html

shared/models.py

shared/static/shared/css/helpers.css

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

...static/shared/vendor/vue-formulate-2.5.3/css/snow.min.css

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

shared/templatetags/shared_filters.py

uniweb/models.py

uniweb/templates/uniweb/base.html