Add seinfo parsing to PackageManagerService.

This patch set allows the PMS to parse the
mac_permissions.xml file which contains the
seinfo values. Each package that is installed
on the device will be assigned an seinfo value
based on policy. This seinfo value will help label
the app process and data directory. Modifications
also include, adjustments to ApplicationInfo.java
to store the seinfo tag per package, adjustments
to installd to communicate the seinfo tag to
libselinux, and finally a set of unit tests.

Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>

Change-Id: I61ad1ea12fb6a9a6d0b108ec163bc4bf4c954b58

Conflicts:
	cmds/installd/commands.c
Added SELinux enforcing status and booleans keys to secure system settings.

Conflicts:
	core/java/android/provider/Settings.java

Change-Id: I01f2a9084dfe7886087b1497070b0d7f2ad8474e
Save off the seinfo value with packages.list.

Patch adds the seinfo label per package to the file.

Change-Id: I01f2a9084dfe7886087b1497070b0d7f2ad8475e
Add APIs to allow Device Admins to change SELinux settings

These calls, added to the Device Admin API, will allow Device Admin apps
to change various SELinux settings, including:
* Toggling SELinux enforcing and permissive modes
* Toggle SELinux booleans
* Load a new SELinux policy file (sepolicy)
* Load new SELinux context files ({property,file,seapp}_contexts)

In order to use these APIs, a Device Admin must first request
USES_POLICY_ENFORCE_SELINUX, then become a SELinux Admin by calling
setSELinuxAdmin(). All other set* calls relevant to SELinux are guarded
by a check against whether the admin is a SELinux Admin.

Otherwise, the style of the set* calls are very similar to the other
calls setting device policy in the Device Admin API. That is, these
calls change the Admin's internal state and then call a sync method to
update the device's state to the Admin's state.

Change-Id: I01f2a9084dfe7886087b1497070b0d7f2ad8476e
Remove SELinux additions from public API

Change-Id: If2e076312b0e411145c1cd900f3ae20d998a0f24
Simplify check during admin removal for whether to cleanup SELinux

Also re-arrange and cleanup

Change-Id: I1261e715d8d04b72f8a29b8a24268d75946d24dc