Unit test for Descriptive Pharmacokinetic Brix Model.

Summary:
setUp, tearDown, Write tests for number of parameter and parameter names.

Add unit tests for: GetModelDisplayName, GetModelType, GetXAxisName, GetXAxisUnit, GetYAxisName, GetYAxisUnit, GetParameterNames, GetNumberOfParameters, GetParameterUnits, GetStaticParameterNames, GetNumberOfStaticParameters, GetStaticParameterUnits.

Add ComputeModelfunctionTest. Compare values to results from Matlab.

Test Plan: Manual

Reviewers: floca, O3 MITK Reviewer Group II

Reviewed By: floca, O3 MITK Reviewer Group II

Subscribers: kislinsk

Differential Revision: https://phabricator.mitk.org/D434