Merge "Provide an API to make USSD calls and read the responses." am: 5a35ed036a am: 0d087ba55e am: 1dc0b2e1a8  -s ours
am: 1ab9a2db47  -s ours

Change-Id: I8aa571bf37ad0c9e9541a54e9022b852c4a8c31d