Make email and nickname case insensitive.

priv/repo/migrations/20170522160642_case_insensivtivity.exs

+defmodule Pleroma.Repo.Migrations.CaseInsensivtivity do
+  use Ecto.Migration
+
+  def up do
+    execute ("create extension if not exists citext")
+    alter table(:users) do
+      modify :email, :citext
+      modify :nickname, :citext
+    end
+  end
+
+  def down do
+    alter table(:users) do
+      modify :email, :string
+      modify :nickname, :string
+    end
+    execute ("drop extension if exists citext")
+  end
+end

test/user_test.exs

@@ -114,6 +114,13 @@ test "gets an existing user" do
       assert user == fetched_user
     end
 
+    test "gets an existing user, case insensitive" do
+      user = insert(:user, nickname: "nick")
+      fetched_user = User.get_or_fetch_by_nickname("NICK")
+
+      assert user == fetched_user
+    end
+
     test "fetches an external user via ostatus if no user exists" do
       fetched_user = User.get_or_fetch_by_nickname("shp@social.heldscal.la")
       assert fetched_user.nickname == "shp@social.heldscal.la"