BIER in non-MPLS netowrks

BIER in non-MPLS netowrks

as decsribed in section 2.2
  ihttps://tools.ietf.org/html/draft-ietf-bier-mpls-encapsulation-10
with BIFT encoding from:
  https://tools.ietf.org/html/draft-wijnandsxu-bier-non-mpls-bift-encoding-00

changes:
1 - introduce the new BIFT lookup table. BIER tables that have an associated
    MPLS label are added to the MPLS-FIB. Those that don't are added to the
    BIER table
2 - BIER routes that have no associated output MPLS label will add a BIFT label.
3 - The BIER FMask has a path-list as a member to resolve via any possible path.

Change-Id: I1fd4d9dbd074f0e855c16e9329b81460ebe1efce
Signed-off-by: Neale Ranns <nranns@cisco.com>