Change the ENVIRONMENT_MAJOR_VERSION to "1"

----Release Notes----
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=89562565

Author: bo-yuan

sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/DataflowPipelineRunner.java

@@ -80,7 +80,7 @@ public class DataflowPipelineRunner extends PipelineRunner<DataflowPipelineJob>
   private DataflowPipelineRunnerHooks hooks;
 
   // Environment version information
-  private static final String ENVIRONMENT_MAJOR_VERSION = "2";
+  private static final String ENVIRONMENT_MAJOR_VERSION = "1";
 
   /**
    * Construct a runner from the provided options.