Add sequence number to Actors

Add sequence number to Actors

When actors with duplicate names are loaded, a way is needed to
determine which should take precedence. Added a sequence number to
Actor to facilitate this.  Unfortunately, couldn't use OrderedServiceImpl,
because it only creates the Actors once, which would break a number
of junit tests.

Issue-ID: POLICY-1625
Signed-off-by: Jim Hahn <jrh3@att.com>
Change-Id: I1ade92f4fe516cfc54bb92d0a3624c67e8981075