Indent license header properly for interfaces.scala.

A very small nit update.

Author: Reynold Xin <rxin@databricks.com>

Closes #3552 from rxin/license-header and squashes the following commits:

df8d1a4 [Reynold Xin] Indent license header properly for interfaces.scala.

sql/core/src/main/scala/org/apache/spark/sql/sources/interfaces.scala

 /*
-* Licensed to the Apache Software Foundation (ASF) under one or more
-* contributor license agreements.  See the NOTICE file distributed with
-* this work for additional information regarding copyright ownership.
-* The ASF licenses this file to You under the Apache License, Version 2.0
-* (the "License"); you may not use this file except in compliance with
-* the License.  You may obtain a copy of the License at
-*
-*    http://www.apache.org/licenses/LICENSE-2.0
-*
-* Unless required by applicable law or agreed to in writing, software
-* distributed under the License is distributed on an "AS IS" BASIS,
-* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-* See the License for the specific language governing permissions and
-* limitations under the License.
-*/
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.apache.spark.sql.sources
 
 import org.apache.spark.annotation.{Experimental, DeveloperApi}
@@ -111,5 +111,3 @@ abstract class PrunedFilteredScan extends BaseRelation {
 abstract class CatalystScan extends BaseRelation {
   def buildScan(requiredColumns: Seq[Attribute], filters: Seq[Expression]): RDD[Row]
 }
-
-