Add draft feature

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

priv/repo/migrations/20191002093208_add_draft_flag_to_events.exs

@@ -0,0 +1,9 @@
+defmodule Mobilizon.Storage.Repo.Migrations.AddDraftFlagToEvents do
+  use Ecto.Migration
+
+  def change do
+    alter table(:events) do
+      add(:draft, :boolean, default: false)
+    end
+  end
+end