Added dataflow.version to parent pom (spring-attic#5074)

Fixes spring-attic#5072

Author: Corneil du Plessis

pom.xml

@@ -57,7 +57,7 @@
 		<javadoc.opts>-Xdoclint:none</javadoc.opts>
 
 		<spring-cloud-dataflow-ui.version>3.3.0-SNAPSHOT</spring-cloud-dataflow-ui.version>
-
+		<dataflow.version>${project.version}</dataflow.version>
 		<spring-cloud-dataflow-common.version>2.10.0-SNAPSHOT</spring-cloud-dataflow-common.version>
 		<spring-cloud-deployer.version>2.8.0-SNAPSHOT</spring-cloud-deployer.version>
 		<spring-cloud-deployer-local.version>2.8.0-SNAPSHOT</spring-cloud-deployer-local.version>