Add Storage Policy Support to list_endpoints

This patch makes list_endpoints policy aware and adds plumbing required
for existing test cases to pass as well as unit tests as needed to
assure policy coverage.

Change-Id: Ia866ddc14ffafda0c791b5fe4f2e81c4178405c2
Implements: blueprint storage-policies
Merge "Add Storage Policy Support to list_endpoints" into feature/ec