Change router commands to take router id

The fact that the commands to debug and manage a router take a tenant id
as argument has been a constant source of confusion. Fix it by making
them take a router id and look up the tenant id.

Change-Id: I7f05319eb854b1b9b4b99fd6e76c778866bcf87a
Merge pull request #166 from dhellmann/rug-ctl-arg-cleanup

Change router commands to take router id