Provides Jasper with a standard mechanism for gaining access to the web.xml
file associated with the current application. This isn't as simple as looking
in /WEB-INF/web.xml. In embedded scenarios, an alternative web.xml may be
provided and in Servlet 3.0 / JSP 2.2 environments an application's web.xml
may be the result of merging a number of web-fragment.xml files and/or
annotations with the main web.xml
Clients *must* ensure that they call close() to clean up resources.