Public profile endorsements (accounts picked by profile owner) (#8146)

app/controllers/accounts_controller.rb

app/controllers/api/v1/accounts/pins_controller.rb

app/helpers/home_helper.rb

app/javascript/mastodon/actions/accounts.js

...script/mastodon/features/account/components/action_bar.js

...t/mastodon/features/account_timeline/components/header.js

.../features/account_timeline/containers/header_container.js

app/javascript/mastodon/reducers/relationships.js

app/javascript/styles/mastodon/widgets.scss

app/models/account.rb

app/models/account_pin.rb

app/models/concerns/account_interactions.rb

app/presenters/account_relationships_presenter.rb

app/serializers/rest/relationship_serializer.rb

app/views/accounts/show.html.haml

config/locales/en.yml

config/routes.rb

db/migrate/20180808175627_create_account_pins.rb

db/schema.rb

spec/fabricators/account_pin_fabricator.rb