Add storage policy support for the Replicator

Adds storoge policy awareness to the replicator service so that it
processes all policy rings according to their type. Thus it also
extends storage policies to include a 'type' element per policy.
The 'type' will default to 'replication' if not specified. Below
it is specified for example purposes:

[storage-policy:0]
name = chicken
type = replication

Unit test code updated to both support policy plumbing as well
as provide coverage for testing with 2 policies in selected
tests.

Change-Id: I721ffc36dfca2bb81f1ce00c3c3d6aec9e27bf43
Implements: blueprint storage-policies
Merge "Add storage policy support for the Replicator" into feature/ec