Bug-2631 - Fixed BGP connection collision detection
-have to examine all connections, in OpenConfirm state
-before, only fully established connections were examined
-connections are kept in map
-remove connection from map, when session goes down
-avoids https://bugs.opendaylight.org/show_bug.cgi?id=2109
-brings dependency of BGPSessionImpl on BGPPeerRegistry
-fixed bgp-identifier conversion to long
Change-Id: I700e8e5a0fb0874731ab2fe013cd7853e44428da
Signed-off-by: Milos Fabian <milfabia@cisco.com>