Added a registration log message to DefaultServiceRegistry.
Changed applicationContext-pollerBackEnd.xml so that it imports Eventd references
via the service registry so that it can be run more easily inside integration tests.
Rearranged integration-tests project into multiple subdirectories and
added an integration test for legacy versions of the remote poller.
Added missing slf4j-api dependency. Added unregisterAll() method to
ServiceRegistry.
Updated @Webapp so that it supports a pathSystemProperty value to pull the
path the the WAR file from a system propery. This makes it easy to integrate
with the maven-dependency-plugin which can set system properties for Maven
artifact paths. Also cleaned up the remote-poller-18 integration test some.