Revision 141043

Here's my idea for approximating derivatives.  It follows the decorator layout of commons-collections.  The main interface point is the UnivariateRealFunctionUtils type which is responisble for creating decorated UnivariateRealFunction objects.  To demostrate the how the decorators could be used, I added the UnivariateRealFunctionUtilsTest class which computes a local maximum of a function using derivative decorators and the default solver.