Added registration timeouts, additional client opts

Added registration call HTTP timeouts to remediate behavior in this issue: https://github.com/PearsonEducation/thalassa-crowsnest/issues/2 . This will allow calls that hang for network related reasons to be quickly cleaned up and retried.

Also added client options for update frequency and default secondsToExpire.
Increased default update period and secondsToExpire

Increased updateFreq and secondsToExpire to widen the race condition window and prefer stale registrations rather than thrashing registrations.
updated README with cli cleint help
0.3.3