Fix spurious warnings in SNSLiveEventDataListener

The live listener class was spewing out warnings about recieving no data
from the SMS because its timeout value was too short.  Fix the timeout
value.

Also, removed all the references to the heartbeat time and heartbeat
packet because we don't need them any more.  (POCO will throw its
timeout exception, so we don't need to manually check for the same
situation.)

Refs #6633