connectionmanager.cpp: cleanup

{} … connections → {} … connection(s)
co → COTURN
dht → DHT
ice → ICE
id → ID
ipv6 → IPv6
needs → requires
not concluant → inconclusive
ok → OK
prefere → prefer
try → attempt
turn → TURN

Change-Id: I5edc5e507440183273e2aed28d3bfc2f872cd1c1