settings: Privacy Guard support

 * Add toggle to InstalledAppDetails to enable/disable privacy guard flag on
   a per-application basis.
 * Add toggle to enable privacy guard by default for applications.

PatchSet: fix crash on uninstall
PatchSet: fix checkbox behaviour
PatchSet: Introduce Privacy Guard Manager
PatchSet: cleanup and comments
PatchSet: add permission filter to show only apps which have critical
	  permissions and privacy guard can hide the information.
	  by default filter is activated
PatchSet: small style correction
PatchSet: move note into an dialog help popup which is shown on first
	  start of PGM and after that available over help menu button

Change-Id: If03aa5319c520b6c4a78887f0f46ef1443ddaa83