set localpath in repository.create

Summary: Since there's no way to set it, it defaults to an empty value. Make the conduit call set up sane default.

Test Plan: Call method, repo get's built with expected localpath.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9842