PrivacyGuard: confirm permissions reset

The button to reset all application permissions to enabled looks
suspiciously like a refresh button. Prompt the user with a confirmation
dialog to make sure they know what they've pressed.

Change-Id: I0444c5bf8e9533feccf890055d34d3200609c6f6
Merge pull request #56 from CyanogenMod/cm-11.0

PrivacyGuard: confirm permissions reset