git-cl status: allow querying just the status of current CL
git-cl status: allow querying just the status of current CL

BUG=620494

Review-Url: https://codereview.chromium.org/2252473004

primiano/depot_tools,CoherentLabs/depot_tools,CoherentLabs/depot_tools,primiano/depot_tools,primiano/depot_tools