MB-100: Use ep_time.h instead of declaring your own time function

Change-Id: I73b8617a763f959d53bdec40f996be32e599a915
Reviewed-on: http://review.couchbase.org/23838
Reviewed-by: Jin Lim <jin@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>