flask/policy: updates from osstest runs

flask/policy: updates from osstest runs

Migration and HVM domain creation both trigger AVC denials that should
be allowed in the default policy; add these rules.

Guest console writes need to be either allowed or denied without audit
depending on the decision of the local administrator; introduce a policy
boolean to switch between these possibilities.

Reported-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Campbell <ian.campbell@citrix.com>