Adding the plugin parent POM to the tree.

This wasn't in there because of the historical reason.
The original layout didn't have the plugin parent POM under the core
source tree.

plugins/update-dependency-hudson-version.rb

-#!/usr/bin/ruby
-# update the version of Hudson that this POM depends on from $1
-require "rexml/document"
-require "rexml/xpath"
-
-# version to update to
-v=ARGV.shift
-
-pom = REXML::Document.new $stdin
-pom.elements.each("//dependency[groupId='org.jvnet.hudson.main']") { |dep|
-  dep.elements["version"].text = v
-}
-pom.write $stdout
-
-

pom.xml

@@ -53,6 +53,7 @@ THE SOFTWARE.
     <module>war</module>
     <module>test</module>
     <module>cli</module>
+    <module>plugins</module>
   </modules>
 
   <scm>