store time as unixtime

add guard against spurious update:
---
D, [2014-07-22T17:23:02.465741 #16013] DEBUG -- : updating record_id
'11704' with result 'ok' and latency '27599790'
undefined method `update' for nil:NilClass
---

27.5 delay? Maybe we already restarted daemon and record was gone?
bump up gemspec