Topic/reqs 298

* Demo tests are in **SingleNameCDSE2ETest** and **CDSIndexE2ETest**.
* IR01, JTD and recovery01 calculations are added to **CDSIndexCalculator**. 
Change to the intrinsic value of a CDS index.
Should note that if the index is priced as a single name CDS, can use InterestRateSensitivityCalculator.parallelIR01