Move Embedded Redis classes to org.springframework.session.redis.embedded

This prevents the embedded redis from being picked up in ComponentScan
in any of the samples unless the @EnableEmebeddedRedis annotation is used.

Polish gh-184

samples/websocket/src/main/java/sample/config/DataSourceConfig.java

@@ -22,8 +22,7 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
-
-import sample.RedisServerPort;
+import org.springframework.session.redis.embedded.RedisServerPort;
 
 @Configuration
 public class DataSourceConfig {