storage: Add GIT_CONFIG_NOGLOBAL=true to git env.
storage: Add GIT_CONFIG_NOGLOBAL=true to git env.

- See https://github.com/opentable/sous/pull/256#pullrequestreview-13308803

samsalisbury/sous,opentable/sous,samsalisbury/sous,samsalisbury/sous,opentable/sous,opentable/sous,samsalisbury/sous,opentable/sous,opentable/sous,samsalisbury/sous