restapi : ovirt shell show vm' not returning all guest attributes

In oVirt-shell 'show vm <guest name>' does not return all
attributes / settings for the given guest.

Document the "All-Content" header in all the resources
that support it.

Change-Id: I65bd2a88deadde3444778e50ec6655850c1d2cc4
Bug-Url: https://bugzilla.redhat.com/1062434
Signed-off-by: Ravi Nori <rnori@redhat.com>