Adding a policy layer for locations APIs

Added a policy layer for the locations APIs of the domain model to
enable the policy checks for image locations changing.

Implements bp: locations-policy

Change-Id: I702723f060f1cc717aca2d99e32d886666c165f8
Signed-off-by: Zhi Yan Liu <zhiyanl@cn.ibm.com>
Merge "Adding a policy layer for locations APIs"