[FLINK-1110] Add createCollectionEnvironment for Scala

flink-scala/src/main/scala/org/apache/flink/api/scala/ExecutionEnvironment.scala

@@ -28,7 +28,7 @@ import org.apache.flink.api.java.typeutils.{ValueTypeInfo, TupleTypeInfoBase}
 import org.apache.flink.api.scala.operators.ScalaCsvInputFormat
 import org.apache.flink.core.fs.Path
 
-import org.apache.flink.api.java.{ExecutionEnvironment => JavaEnv}
+import org.apache.flink.api.java.{ExecutionEnvironment => JavaEnv, CollectionEnvironment}
 import org.apache.flink.api.common.io.{InputFormat, FileInputFormat}
 
 import org.apache.flink.api.java.operators.DataSource
@@ -391,6 +391,16 @@ object ExecutionEnvironment {
  new ExecutionEnvironment(javaEnv)
  }
 
+ /**
+ * Createa an execution environment that uses Java Collections underneath. This will execute in a
+ * single thread in the current JVM. It is very fast but will fail if the data does not fit into
+ * memory. This is useful during implementation and for debugging.
+ * @return
+ */
+ def createCollectionsEnvironment: ExecutionEnvironment = {
+ new ExecutionEnvironment(new CollectionEnvironment)
+ }
+
  /**
  * Creates a remote execution environment. The remote environment sends (parts of) the program to
  * a cluster for execution. Note that all file paths used in the program must be accessible from