anchor/vaultaire-query — pull request #5 by oswynb (2014-09-12 07:49:11+00:00)
Title: Added fold for cumulative openstack data

Openstack cumulative data is from last startup. So when we process cumulative data we need to account for this.

Since (excluding restarts) each point is strictly non-decreasing, we simply use a modified fold to deal with the case where the latest point is less than the second latest point (indicating a restart)