Added validation example for Problem 1.2 of Class (2009)

[francoishamon]

This PR adds a validation case for the second problem (Problem 1.2) proposed in the benchmark paper: "A benchmark study on problems related to CO 2 storage in geologic formations", Class et al, 2009.

I got the following result, which is the best I could do given the differences in the other codes' results and the information provided in the paper.

This PR requires some code fixes in the CO2-brine fluid package that will be done in a separate PR.

This PR will require a rebaseline to add a smoke test based on a coarse version of the problem (I still haven't added this coarse problem to the PR).