AppArmor: userspace interfaces

The /proc/<pid>/attr/* interface is used for process introspection and
commands.  While the apparmorfs interface is used for global introspection
and loading and removing policy.

The interface currently only contains the files necessary for loading
policy, and will be extended in the future to include sysfs style
single per file introspection inteface.

The old AppArmor 2.4 interface files have been removed into a compatibility
patch, that distros can use to maintain backwards compatibility.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>