Updated SpicePosition unit test to test multi-segment polynomials and better...

Updated SpicePosition unit test to test multi-segment polynomials and better test polynomial over hermite.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/branches/PiecewisePolynomials@8269 41f8697f-d340-4b68-9986-7bafba869bb8