upgrade release plugin to 2.0

git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@985217 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 13fbfbc..3661e20 100755
--- a/pom.xml
+++ b/pom.xml
@@ -993,6 +993,7 @@
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-release-plugin</artifactId>
+          <version>2.0</version>
           <configuration>
             <autoVersionSubmodules>true</autoVersionSubmodules>
             <allowTimestampedSnapshots>false</allowTimestampedSnapshots>