Disable to create duplicate (with same IP Address) PCEP sessions.

Disable to create duplicate (with same IP Address) PCEP sessions.

Moved duplicate session handling into AbstractSessionNegtiatorFactory (PCEPPeerRegistry),
to be usable for all session negotiators created by. PCEPPeerRegistry also handle session-id caching.

Session ref. entries stored in bi-map were identifed by byte array (raw IP Address of client),
casuing that already existing session in bi-map were not look-up properly => allowing to create duplicate sessions.
Changed type of bi-map's key to wrapper of byte array.

Fixed also removing of session refs. from map on channel close. Turned bi-map to map, since inverse map is not used anymore.

pcc-mock is reusing this code - need to create session negotiator factory per pcc.

Change-Id: I85670b083b6ea832f8b9a4891c812845174f03ff
Signed-off-by: Milos Fabian <milfabia@cisco.com>