Bluetooth: Disconnect SCO for In-Band Ringtone.

 -Disconnect SCO when remote sends RING indication
  even after disabling in-band ringtone.

Change-Id: I6955de8a7dd192aea492b768dd80343a32ca1cc0
CRs-Fixed: 751075

Bluetooth : Stop the ring when HS disconnects.

This change makes sure that Ring is stopped
when HF is disconnected.

Change-Id: I3e150089ad799133101f9466f5c7aa042a1e600e
CRs-Fixed: 748283

Bluetooth: Abandon Audio Focus.

 - After call is rejected by user abandon
   audio focus.
 - When audio focus abandonment is delayed
   A2dp sink cannot resume.

Change-Id: I5a02b639427e711ac695f551469261549a62797e

Add support for AT+CGMI and AT+CGMM

Added support for AT+CGMI and AT+CGMM commands. AT+CGMI gets
the AG manufacturer identifacation. AT+CGMM gets the AG
manufacturer model. The information is broadcasted as strings.

CRs-fixed: 844824
Change-Id: I9d53e378f6651ee0afd94b5525189c17cfeffa76