code: function loadMigrationFile(vault, version) {
  	var migratorPath = pathJoin(configuration.getMigrationsPath(vault.name), version);
  
  	return require(migratorPath);
  }
docs: Loads a file from the project's /lib/archivist/migrations/VAULT folder
  
  @param {Object} vault   The vault for which to load a migration file.
  @param {string} version The specific version of the migration.
  @returns {Object}       A module containing an 'up' and optionally a 'down' method.