Place API endpoint connection attemps within try..except blocks

Ensure servo doesn't die out on network troubles. These connection
attempts will be retried in the following cycles.
Use counters instead of time comparisons for delay loops

Absolute time comparison has potential problems with backward clock
changes. This can manifest when servo is up and running before we
get a time update from NTP. A counter provides the same functionality
with adequate accuracy.
Merge pull request #9 from hnousiainen/load-balancer-servo-loop

Use counters instead of timestamps in load balancer servo loops