[FLINK-6312] [build] Update curator version to 2.12.0

The updated curator version includes a bugfix for a potential block

flink-contrib/flink-storm-examples/pom.xml

@@ -84,6 +84,10 @@ under the License.
 					<groupId>org.apache.storm</groupId>
 					<artifactId>storm-core</artifactId>
 				</exclusion>
+				<exclusion>
+					<groupId>org.apache.curator</groupId>
+					<artifactId>curator-framework</artifactId>
+				</exclusion>
 			</exclusions>
 		</dependency>
 

flink-runtime/src/test/java/org/apache/flink/runtime/checkpoint/ZooKeeperCompletedCheckpointStoreTest.java

@@ -22,7 +22,7 @@ import org.apache.curator.framework.CuratorFramework;
 import org.apache.curator.framework.api.BackgroundCallback;
 import org.apache.curator.framework.api.CuratorEvent;
 import org.apache.curator.framework.api.CuratorEventType;
-import org.apache.curator.framework.api.Pathable;
+import org.apache.curator.framework.api.ErrorListenerPathable;
 import org.apache.curator.utils.EnsurePath;
 import org.apache.flink.api.java.tuple.Tuple2;
 import org.apache.flink.runtime.concurrent.Executors;
@@ -128,12 +128,12 @@ public class ZooKeeperCompletedCheckpointStoreTest extends TestLogger {
 				.delete()
 				.deletingChildrenIfNeeded()
 				.inBackground(any(BackgroundCallback.class), any(Executor.class))
-		).thenAnswer(new Answer<Pathable<Void>>() {
+		).thenAnswer(new Answer<ErrorListenerPathable<Void>>() {
 			@Override
-			public Pathable<Void> answer(InvocationOnMock invocation) throws Throwable {
+			public ErrorListenerPathable<Void> answer(InvocationOnMock invocation) throws Throwable {
 				final BackgroundCallback callback = (BackgroundCallback) invocation.getArguments()[0];
 
-				Pathable<Void> result = mock(Pathable.class);
+				ErrorListenerPathable<Void> result = mock(ErrorListenerPathable.class);
 
 				when(result.forPath(anyString())).thenAnswer(new Answer<Void>() {
 					@Override

pom.xml

@@ -101,7 +101,7 @@ under the License.
 		<chill.version>0.7.4</chill.version>
 		<asm.version>5.0.4</asm.version>
 		<zookeeper.version>3.4.6</zookeeper.version>
-		<curator.version>2.8.0</curator.version>
+		<curator.version>2.12.0</curator.version>
 		<jackson.version>2.7.4</jackson.version>
 		<metrics.version>3.1.0</metrics.version>
 		<junit.version>4.12</junit.version>