R1:213e4ec9b553

Add a missing (int) cast to diff IDs for new "transaction.search" method

Summary: These come out of the database as strings (see T12678), force them to integers for the API.

Test Plan: Called `transaction.search`, got integers in JSON instead of strings.

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D18476