jar:sign mojo seems to be a new feature in 2.1

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@2147 71c3de6d-444a-0410-be80-ed276b4c234a

jnlp-agent/pom.xml

@@ -15,6 +15,7 @@
     <plugins>
       <plugin>
         <artifactId>maven-jar-plugin</artifactId>
+        <version>2.1</version>
         <executions>
           <execution>
             <goals>

remoting/pom.xml

@@ -177,6 +177,7 @@
       </plugin>
       <plugin>
         <artifactId>maven-jar-plugin</artifactId>
+        <version>2.1</version>
         <configuration>
           <archive>
             <manifest>