log detailed failure of ip address check for poor-man's alerts
log detailed failure of ip address check for poor-man's alerts

We're seeing spurious ip address change warnings and we don't
understand how it happens. Logging errors should help us understand
and fix this issue.

Change-Id: I884920dc2e8a26a086af59a7259c7f0d4e600f5a
Reviewed-on: http://review.couchbase.org/8079
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Filipe David Borba Manana <e0fcd583df77ec6c08e6d1257619cc1216ddc994@gmail.com>

t3rm1n4l/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,daverigby/ns_server,vzasade/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,ceejatec/ns_server,ceejatec/ns_server,nimishzynga/ns_server,membase/ns_server,membase/ns_server,daverigby/ns_server,ceejatec/ns_server,daverigby/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,pavel-blagodov/ns_server,vzasade/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,ceejatec/ns_server,membase/ns_server,membase/ns_server,mschoch/ns_server,daverigby/ns_server,membase/ns_server,nimishzynga/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,vzasade/ns_server,vzasade/ns_server,mschoch/ns_server,nimishzynga/ns_server,nimishzynga/ns_server