Creates the tables used by FIX.Session.Store.Postgres.

Call up/1 and down/1 from a migration in the host application:

defmodule MyApp.Repo.Migrations.AddFixSessionTables do
  use Ecto.Migration

  def up, do: FIX.Session.Store.Postgres.Migrations.up()
  def down, do: FIX.Session.Store.Postgres.Migrations.down()
end