Only auto-configure Reduce if Lettuce is on the classpath

Fixes #226

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/redis/RedisAutoConfiguration.java

@@ -38,13 +38,15 @@ import org.springframework.data.redis.core.RedisOperations;
 import org.springframework.data.redis.core.RedisTemplate;
 import org.springframework.data.redis.core.StringRedisTemplate;
 
+import com.lambdaworks.redis.RedisClient;
+
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Spring Data's Redis support.
  * 
  * @author Dave Syer
  */
 @Configuration
-@ConditionalOnClass({ LettuceConnection.class, RedisOperations.class })
+@ConditionalOnClass({ LettuceConnection.class, RedisOperations.class, RedisClient.class })
 public class RedisAutoConfiguration {
 
 	@Configuration