Spring quickstarts added

The added quickstarts are as follows:
Greeter-Spring: Simple Greeter Application using Spring 3.1
Petclinic-Spring: Advanced level Spring quickstart using Spring 3.1
Travel-Spring: Advanced level Spring quickstart using Spring 3.1
Kitchensink-Spring 5 Variants:
   -- Basic kitchensink using spring 3.1 with rest and spring mvc
   -- 4 other variants using spring 3.2 each showcase an additional feature introduced in spring 3.2