Follow our blog post on normalization of monetary amounts for the global cube

[larjohn]

Currently, the global cube implements a certain money normalization strategy.

We should make it compatible with the blog post on:
https://github.com/openbudgets/openbudgets.github.io/blob/comparing-money/_posts/2016-07-07-comparing-money-across-time-and-space.md

[pwalsh]

Cc @akariv