Long-press back kill app cleanup

Change-Id: Ida791dca1fbfdc2beccf6ff727b67df56f1956a4

Conflicts:
	core/res/res/values/strings.xml
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
framework: customizable kill app via back key timeout

Allows the time it takes for the back key to kill an app
to be customized via overlay.

Change-Id: Iaa43f81ee448ae7a7663254a830011a0bca5e60f

Conflicts:
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java