InCallUI: Update AddParticipant and Modifycall buttons when reject call

When reject a call, the AddParticipant and Modifycall buttons are not
updated because the isEnabled is false, so they are still visible.

Set AddParticipant and Modifycall invisible when isEnable is false.

CRs-Fixed: 621909

Conflicts:
	src/com/android/incallui/CallButtonPresenter.java

Change-Id: I35513bd5b98376721596354a24d6b01fa07dab9d
VolumeBoost : Add support for TTY HCO mode.

Enable volume boost icon in TTY HCO(TTY + Earpiece) in UI layer.

CRs-fixed: 530337

Conflicts:
	src/com/android/incallui/CallCardFragment.java

Change-Id: Ic60a561e0ed9dad4ccb87cea964b24cfc4783883