Add polls (#10111)

* Add polls

Fix #1629

* Add tests

* Fixes

* Change API for creating polls

* Use name instead of content for votes

* Remove poll validation for remote polls

* Add polls to public pages

* When updating the poll, update options just in case they were changed

* Fix public pages showing both poll and other media

db/migrate/20190225031541_create_polls.rb

@@ -0,0 +1,17 @@
+class CreatePolls < ActiveRecord::Migration[5.2]
+  def change
+    create_table :polls do |t|
+      t.belongs_to :account, foreign_key: { on_delete: :cascade }
+      t.belongs_to :status, foreign_key: { on_delete: :cascade }
+      t.datetime :expires_at
+      t.string :options, null: false, array: true, default: []
+      t.bigint :cached_tallies, null: false, array: true, default: []
+      t.boolean :multiple, null: false, default: false
+      t.boolean :hide_totals, null: false, default: false
+      t.bigint :votes_count, null: false, default: 0
+      t.datetime :last_fetched_at
+
+      t.timestamps
+    end
+  end
+end