Add HazelcastSessionRepository

This commit improves existing Hazelcast support, which is based on
MapSessionRepository, with dedicated HazelcastSessionRepository
that implements the FindByIndexNameSessionRepository contract.

Also a new hazelcast-spring-session module was added to provide
dependency management for Hazelcast support.

Fixes gh-544

samples/hazelcast-spring/src/main/java/sample/SecurityInitializer.java

@@ -22,7 +22,7 @@ import org.springframework.security.web.context.AbstractSecurityWebApplicationIn
 public class SecurityInitializer extends AbstractSecurityWebApplicationInitializer {
 
 	public SecurityInitializer() {
-		super(SecurityConfig.class, Config.class);
+		super(SecurityConfig.class, SessionConfig.class);
 	}
 }
 // end::class[]