InCallUI: Fix the repeated appending for the input number from HID.

In DTMFKeyListener,the input numbers would be appended twice by its
parent and itself.
Solution: Don't append the input numbers in DTMFKeyListener.

Change-Id: Ie3f6049a5d4bd7aa541438ce519d86a89e520f63
CRs-Fixed: 656603
TeleService: Show answer UI and hide manage conference panel for MT CALL

The answer UI is shown, but it is covered by the manage conference
call fragment.

When show the answer UI, hide the manage conference call fragment.

CRs-Fixed: 657336

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

Change-Id: Ifea4e08e7ea7e2d6dd61632b8cc5d2d92aa09df3