Fix build after a recent change to goraft.

Summary:
The timeout used to be hard-coded 150ms, but is now a required parameter
to NewHTTPTransporter.

You may need to update your copy of goraft after this commit.

Test Plan: go test ./...

Reviewers: spencerkimball, andybons

Reviewed By: andybons

Differential Revision: http://phabricator.andybons.com/D17