Work on actors

* Implement group GraphQL APIs
* Change Actors changeset to properly set urls
* Remove old actors indexes and add some new ones

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

priv/repo/migrations/20181203092128_change_actors_indexes.exs

@@ -0,0 +1,19 @@
+defmodule Mobilizon.Repo.Migrations.ChangeActorsIndexes do
+  use Ecto.Migration
+
+  def up do
+    drop index("actors", [:preferred_username, :domain], name: :actors_preferred_username_domain_index)
+    drop index("actors", [:name, :domain], name: :accounts_username_domain_index)
+    execute "ALTER INDEX accounts_pkey RENAME TO actors_pkey"
+    create index("actors", [:preferred_username, :domain, :type], unique: true)
+    create index("actors", [:url], unique: true)
+  end
+
+  def down do
+    create index("actors", [:preferred_username, :domain], name: :actors_preferred_username_domain_index)
+    create index("actors", [:name, :domain], name: :accounts_username_domain_index)
+    execute "ALTER INDEX actors_pkey RENAME TO accounts_pkey"
+    drop index("actors", [:preferred_username, :domain, :type])
+    drop index("actors", [:url])
+  end
+end