state/api/agent: Entity takes a tag, not a string of a tag.
juju/api/usermanager: add UserInfo

Add UserInfo method to the API client.
Merge pull request #91 from waigani/user-detail-clientapi

juju/api/usermanager: add UserInfo

UserInfo was recently added to the server API. This PR adds the client side UserInfo method.
Merge pull request #120 from davecheney/fix-why-does-entity-take-a-string-and-not-a-tag

state/api/agent: Entity takes a tag, not a string of a tag.
Add user info cmd