Specify an ssh port for Diffusion when running against the grain
Summary: We run git on a different port than 22, so would like to reflect this change in the UI.
Test Plan: Set diffusion.ssh-port in settings, then make sure it's reflected on the Diffusion repository Clone URI.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley
CC: Korvin, epriestley, aran, dctrwatson
Differential Revision: https://secure.phabricator.com/D7755