added isCluster method

Author: jruaux

src/main/java/com/redislabs/testcontainers/RedisClusterContainer.java

@@ -34,6 +34,12 @@ protected RedisClusterContainer(final String dockerImageName) {
         waitingFor(Wait.forLogMessage(".*Cluster state changed: ok*\\n", 1));
     }
 
+    @Override
+    public boolean isCluster() {
+        return true;
+    }
+
+
     public RedisClusterContainer withKeyspaceNotifications() {
         setDockerImageName(KEYSPACE_NOTIFICATIONS_IMAGE_NAME);
         return this;

src/main/java/com/redislabs/testcontainers/RedisContainer.java

@@ -4,4 +4,6 @@ public interface RedisContainer {
 
     String getRedisURI();
 
+    boolean isCluster();
+
 }

src/main/java/com/redislabs/testcontainers/RedisModulesContainer.java

@@ -11,6 +11,11 @@ public RedisModulesContainer() {
         this(DEFAULT_IMAGE_NAME.withTag(DEFAULT_TAG));
     }
 
+    @Override
+    public boolean isCluster() {
+        return false;
+    }
+
     protected RedisModulesContainer(final DockerImageName dockerImageName) {
         super(dockerImageName);
     }

src/main/java/com/redislabs/testcontainers/RedisStandaloneContainer.java

@@ -16,6 +16,11 @@ protected RedisStandaloneContainer(final DockerImageName dockerImageName) {
         super(dockerImageName);
     }
 
+    @Override
+    public boolean isCluster() {
+        return false;
+    }
+
     @SuppressWarnings("unchecked")
     public <C extends RedisStandaloneContainer> C withKeyspaceNotifications() {
         withCopyFileToContainer(MountableFile.forClasspathResource("redis-keyspace-notifications.conf"), "/data/redis.conf");