Bluetooth: Add connected/disconnected management events

This patch adds connected and disconnected managment events to track the
connection status to remote devices. The events map directly to
successful connection complete and disconnection complete HCI events for
ACL links.

Signed-off-by: Johan Hedberg <johan.hedberg@nokia.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>