[#477] Added FTS index for users. Fixed failing test.

priv/repo/migrations/20190115085500_create_user_fts_index.exs

@@ -0,0 +1,17 @@
+defmodule Pleroma.Repo.Migrations.CreateUserFtsIndex do
+  use Ecto.Migration
+
+  def change do
+    create index(
+             :users,
+             [
+               """
+               (setweight(to_tsvector('simple', regexp_replace(nickname, '\\W', ' ', 'g')), 'A') ||
+               setweight(to_tsvector('simple', regexp_replace(coalesce(name, ''), '\\W', ' ', 'g')), 'B'))
+               """
+             ],
+             name: :users_fts_index,
+             using: :gin
+           )
+  end
+end