Topic/plat 6640 part2

This is the bulk of the new caplet stripping code. The idea is to have a system that makes it easy to add new models. Only a few models are implemented here. Note, some tests are marked as TestGroup.UNIT_SLOW, which will reduce the test coverage on systems that do not run these tests.   
There is a CapletStripper interface. CapletStrippingImp (as in implementation) does all the 'work' and can be used directly. The classes that implement CapletStripper encapsulate a particular model, have a higher level API and wrap CapletStrippingImp