Sean Chittenden 3a6be9cab0 Add a helper function DurationMinusBuffer() to calculate an interval
used to schedule a TTL check.  e.g.

d := lib.DurationMinusBuffer(60 * time.Duration, 10 * time.Second, 16)

will return a duration between 46.875s and 50s.
2016-04-23 09:06:54 -07:00
..
2016-03-30 11:47:37 -07:00
2016-03-30 11:47:37 -07:00