[WHISKER-13] Error during site generation with HelpMojo and Java8
- The version for maven-plugin-plugin was only specified for reporting, but not for build. Specifying it for build made the site generation succeed on Java 8.

git-svn-id: https://svn.apache.org/repos/asf/creadur/whisker/trunk@1622985 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/apache-whisker-plugin4maven/pom.xml b/apache-whisker-plugin4maven/pom.xml
index 931c20f..afab215 100644
--- a/apache-whisker-plugin4maven/pom.xml
+++ b/apache-whisker-plugin4maven/pom.xml
@@ -110,6 +110,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-plugin-plugin</artifactId>
+        <version>${mavenPluginPluginVersion}</version>
         <configuration>
           <goalPrefix>plugin</goalPrefix>
           <!-- see already solved bug http://jira.codehaus.org/browse/MNG-5346 describes the problems we experience on Jenkins-CI (20140822)-->