Add whitespace-preserving attribute to Maven file

Change-Id: I0afc36935ce93093b51de373b426bcf8ef5d5ee8
diff --git a/features/org.eclipse.emf.henshin.sdk/pom.xml b/features/org.eclipse.emf.henshin.sdk/pom.xml
index 377eff9..5835aa3 100644
--- a/features/org.eclipse.emf.henshin.sdk/pom.xml
+++ b/features/org.eclipse.emf.henshin.sdk/pom.xml
@@ -26,7 +26,7 @@
             <goal>source-feature</goal>
           </goals>
           <configuration>
-            <labelSuffix> Sources</labelSuffix>
+            <labelSuffix xml:space="preserve"> Sources</labelSuffix>
             <excludes>
               <plugin id="de.tuberlin.eecs.agg"/>
             </excludes>