Constructors have been added to both ContextLoader and
ContextLoaderListener to support instance-based programmatic
registration of listeners within ServletContainerInitializer
implementations in Servlet 3.0+ environments, and more particularly
when using Spring 3.1's WebApplicationInitializer SPI.
Issue: SPR-7672
git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@4382 50f2f4bb-b051-0410-bef5-90022cba6387