Change OS_REGION to OS_REGION_NAME

Dolph made a comment a while back saying region_name should be
region which I did.  Talked with Dean about this and he dug
his heels in saying it should be region_name.  All the CLIs
are using region_name.

Change-Id: I212eb4ec96a59650226ae5f5b0172c40c25dec90
Merge "Change OS_REGION to OS_REGION_NAME"