in mig.Agent, declare Tags as a map for Agent type
in mig.Agent, declare Tags as a map for Agent type

In 4cd3867, agent tags were converted to a map[string]string from an
interface to make the structure more easily modified from configuration
files.

Fix up the Agent type here so the tags are defined correctly.

mozilla/mig,ameihm0912/mig,mozilla/mig,mozilla/mig,ameihm0912/mig,mozilla/mig,ameihm0912/mig,mozilla/mig