Ensure that domain and appdomain attributes are assigned.

Prevent defining any process types without the domain attribute
so that all allow and neverallow rules written on domain are
applied to all processes.

Prevent defining any app process types without the appdomain
attribute so that all allow and neverallow rules written on
appdomain are applied to all app processes.

Change-Id: I4cb565314fd40e1e82c4360efb671b175a1ee389
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>