Settings: Less Notification Sounds (2/2)

Ported 'Bluewall Firewall' from AOKP

mutes notification sounds for an application for <X> seconds after playing

Patchset 2: rebase
Patchset 3: minor fixes based on suggestions from Jeff and Lars

Change-Id: I4665010c819729088e64b13db6a199d474c89573