Unit test for standard Tofts model

Summary:
Set up all Standard Tofts Model functions to be tested.

Add unit tests to test suite: GetModelType,GetParameterNames,GetNumberOfParameters,GetParameterUnits,GetDerivedParameterNames,GetNumberOfDerivedParameters,GetDerivedParameterUnits,

Add test data for AIF, time grid and parameters from real data. Add unit test for computeModelFunction and ComputeDerivedParameters.

Test Plan: manual testing

Reviewers: floca

Reviewed By: floca

Differential Revision: https://phabricator.mitk.org/D543