Fix runtime permissinos toggling and relax XML parsing.

1. Fixed the case where runtime permissons can be toggled by a
   developer via a system property.

2. Relaxed the runtime permission XML parsing to be more fault
   toelrant and consistent wiht the reset of the package manager
   parse code.

3. Fixed a deadlock due to calling in to the activity manager
   with the package manager lock held to kill an app.

Change-Id: I11dfb57ad4d8119baea79227dc2a3fe5e2208515