Fix EmergencyDialer button on devices without telephony hardware

This fixes showing the emergency dialer on devices without telephony.
Two fixes were required: 1. Move emergency dialer code to the view
that contains it (KeyguardSelectorView).  2. Always call onPause()
or onResume() in onScreenTurnedOff() and onScreenTurnedOn(), respectively.

Fixes bug 7117895

Change-Id: I96769fdda8478b6b60f46f7470bed2279ea2de72