Bumping AOSP Contacts version to 1.4.15
am: d2ac793647  -s ours

* commit 'd2ac79364766e892102330bbbf0323f4439db3f6':
  Bumping AOSP Contacts version to 1.4.15

Change-Id: I759cf706ac774a791cfc1082ea62df9ae0b92e5d