Add support for proprietary libaudio voice quality filter

This single commit add support for this feature, which is also
called "Crystal Talk"

Add support for an overlay config key like "motoVoiceQualityConfig"
present in motorola libaudio.

Change-Id: I8752cd07340e6caf53ba8e2f19d24a361de22bee

Conflicts:

	res/values/strings.xml
	src/com/android/phone/PhoneUtils.java