Minimal model updating case

[markusdregi]

Task
Created an ERT-case for doing model updates with the model being nothing but a second degree polynomial.

See the README for a more thorough introduction.

Pre un-WIP checklist

• Statoil tests pass locally
• Have completed graphical integration test steps

[andreabrambilla]

This is great, we really need an example like this for the EnKF! 👏 👍
Shall we actually have a test that runs this and checks that the value of the parameters at the end?

And we should definitely have a time dependent version, which would be more similar to the real cases EnKF is used for

[markusdregi]

I agree that we should have a test for this. I though that this could be the very first application of #165 when that has been merged.

And yes, we can also make a version that depends on time. Perhaps we can generate data for two different polynomials, and then have input to the polynomials be time 👍

I suggest however that we merge this one as is. Get testing when #165 is done and then extend with more cases after that..

[andreabrambilla]

yes yes, my comments were more for "future development" ;)
Nice job 👍