Release container fix.

The release branch uses the project version, not a daily snapshot.

Author: wcn3

pom.xml

@@ -106,7 +106,7 @@
     <beam.version>2.1.0</beam.version>
 
     <dataflow.release_name>Google Cloud Dataflow SDK for Java</dataflow.release_name>
-    <dataflow.container_version>${project.version}-20170823</dataflow.container_version>
+    <dataflow.container_version>${project.version}</dataflow.container_version>
     <dataflow.legacy_environment_major_version>6</dataflow.legacy_environment_major_version>
     <dataflow.fnapi_environment_major_version>1</dataflow.fnapi_environment_major_version>
   </properties>